Update GUIDELINES

CONTRIBUTING.md

+# Contributing
+
+The CORSIKA project is committed to fostering and preserving a
+diverse, welcoming community; all participants are expected to
+respect that. 
+
+- [Getting Started](#getting-started)
+    - [Very first steps](#very-first-steps)
+    - [Opening issues](#opening-issues)
+    - [Participating in discussions](#participating-in-discussions)
+    - [Improving and reviewing docs](#improving-and-reviewing-docs)
+    - [Reviewing and testing changes](#reviewing-and-testing-changes)
+- [Proposing and making changes](#proposing-and-making-changes)
+	- [Finding something to work on](#finding-something-to-work-on)
+    - [Before you start](#before-you-start-work)
+    - [Before you open your PR](#before-you-open-your-pr)
+    - [Review process](#review-process)
+- [Getting more involved](#getting-more-involved)
+
+## Getting started
+
+Not sure where to start? If you haven't already, take a look at the 
+[docs](http://xi-editor.github.io/xi-editor/docs.html) to get a better
+sense of the project. Read through some issues and some open PRs, to
+get a sense for the habits of existing contributors. Drop by the #xi
+channel on [irc.mozilla.org](https://mozilla.logbot.info/xi) to follow
+ongoing discussions or ask questions. Clone the repos you're
+interested in, and make sure you can build and run the tests. If you
+can't, open an issue, and someone will try to help. Once you're up and
+running, there are a a number of ways to participate:
+
+### Opening issues
+
+If you have a question or a feature request or think you've found a bug,
+please open an issue. When opening an issue, include any details that
+might be relevant: for a bug this might be the steps required to
+reproduce; for a feature request it might be a detailed explanation of
+the behaviour you are imagining, an outline of how it would be used,
+and/or examples of how this feature is used in other editors.
+
+#### Before you open an issue
+
+Before opening an issue, **try to identify where the issue belongs**.
+Is it a problem with the frontend or with core? The frontend is 
+responsible for drawing windows and UI, and handling events; the core
+is responsible for most everything else. Issues with the frontend
+should be opened in that frontend's repository, and issues with
+core should be opened in the 
+[xi-editor](https://github.com/xi-editor/xi-editor/issues) repo.
+
+Finally, before opening an issue, **use github's search bar** to make
+sure there isn't an existing (open or closed) issue for your particular
+problem.
+
+### Participating in discussions
+
+An _explicit_ goal of xi-editor is to be an educational resource.
+Everyone is encouraged to participate in discussion issues (issues with
+the 'discussion' or 'planning' labels), and we expect people
+participating in discussions to be respectful of the fact that we all
+have different backgrounds and levels of experience. Similarly, if
+something is confusing, feel free to ask for clarification! If you're
+confused, other people probably are as well.
+
+### Improving and reviewing docs
+
+If the docs are unclear or incomplete, please open an issue or a PR to
+improve them. This is an especially valuable form of feedback from new
+contributors, who are seeing things for the first time, and will be best
+positioned to identify areas that need improvement.
+
+### Reviewing and testing changes
+
+One of the best ways to get more familiar with the project is by reading
+other people's pull requests. If there's something in a commit that you
+don't understand, this is a great time to ask for clarification. Testing
+changes is also very helpful, especially for bug fixes or feature
+additions. Check out a change and try it out; does it work? Can you find
+edge cases? Manual testing is very valuable. For more information on
+reviews, see [code review process](#review-process).
+
+
+## Proposing and making changes
+
+### Finding something to work on
+
+If you're looking for something to work on, a good first step is to browse
+the [issues](https://github.com/xi-editor/xi-editor/issues). Specifically,
+issues that are labeled 
+[help wanted](https://github.com/xi-editor/xi-editor/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22) and/or
+[easy](https://github.com/xi-editor/xi-editor/issues?q=is%3Aissue+is%3Aopen+label%3Aeasy)
+are good places to start. If you can't find anything there, feel free to ask
+on IRC, or play around with the editor and try to identify something that
+_you_ think is missing.
+
+### Before you start work
+
+Before starting to work on an issue, consider the following:
+    
+- _Is it a bugfix or small change?_ If you notice a small bug somewhere,
+ and you believe you have a fix, feel free to open a pull request directly.
+
+- _Is it a feature?_ If you have an idea for a new editor feature that is
+ along the lines of something that already exists (for instance, adding a
+ new command to reverse the letters in a selected region) _consider_ 
+ opening a short issue beforehand, describing the feature you have in mind.
+ Other contributors might be able to identify possible issues or
+ refinements. This isn't _necessary_, but it might end up saving you work,
+ and it means you will get to close an issue when your PR gets merged,
+ which feels good.
+
+- _Is it a major feature, affecting for instance the behaviour or appearance
+ of a frontend, or the API or architecture of core?_ Before working on a 
+ large change, please open a discussion/proposal issue. This should describe
+ the problem you're trying to solve, and the approach you're considering; 
+ think of this as a 'lite' version of Rust's 
+ [RFC](https://github.com/rust-lang/rfcs) process. 
+
+
+### Before you open your PR
+
+Before pressing the 'Create pull request' button, 
+
+- _Run the tests_. It's easy to accidentally break something with even a small 
+ change, so always run the tests locally before submitting (or updating) a PR.
+ You can run all checks locally with the `xi-editor/rust/run_all_checks`. script.
+
+- _Add a message for your reviewers_. When submitting a PR, take advantage
+ of the opportunity to include a message. Your goal here should be to help
+ your reviewers. Are there any parts of your change that you're uncertain
+ about? Are there any non-obvious explanations for some of your decisions?
+ If your change changes some behaviour, how might it be tested?
+
+- ***Be your own first reviewer***. On the page where you enter your message,
+ you have a final opportunity to see your PR _as it will be seen by your 
+ reviewers_. This is a great opportunity to give it one last review, yourself.
+ Imagine that it is someone else's work, that you're reviewing: what comments 
+ would you have? If you spot a typo or a problem, you can push an update in 
+ place, without losing your PR message or other state.
+
+- _Add yourself to the AUTHORS file_. If this is your first substantive pull 
+request in this repo, feel free to add yourself to the AUTHORS file.
+
+### Review process
+
+Every non-trivial pull request goes through review. Everyone is welcome to 
+participate in review; review is an excellent time to ask questions about
+code or design decisions that you don't understand.
+
+All pull requests must be approved by an appropriate reviewer before they
+are merged. For bug fixes and smaller changes, this can be anyone who has
+commit rights to the repo in question; larger changes (changes which add a
+feature, or significantly change behaviour or API) should also be approved by
+a maintainer.
+
+Before being merged, a change must pass 
+[CI](https://en.wikipedia.org/wiki/Continuous_integration).
+
+#### Responsibilites of the approving reviewer
+
+If you approve a change, it is expected that you:
+- understand what the change is trying to do, and how it is doing it
+- have manually built and tested the change, to verify it works as intended
+- believe the change generally matches the idioms, formatting rules,
+and overall coding style of the relevant repo
+- are ready and able to help resolve any problems that may be introduced by
+merging the change.
+
+If a PR is made by a contributor who has write access to the repo in question, 
+they are responsible for merging/rebasing the PR after it has been approved; 
+otherwise it will be merged by the reviewer.
+
+If a patch adds or modifies behaviour that is observable in the client, 
+the reviewer should build the patch and verify that it works as expected.
+
+### After submitting your change
+
+You've done all this, and submitted your patch. What now?
+
+_Read other PRs_. If you're waiting for a review, it's likely that other
+pull requests are waiting for review as well. This can be a good time
+to go and take a look at what other work is happening in the project;
+and if another PR has review comments, it might provide a clue to the
+type of feedback you might expect.
+
+_Patience_. As a general goal, we try to respond to all pull requests
+within a few days, and to do preliminary review within a week, but we
+don't always succeed. If you've opened a PR and haven't heard from
+anyone, feel free to comment on it, or stop by the IRC channel, to ask
+if anyone has had a chance to take a look. It's very possible that it's
+been lost in the shuffle.
+
+## Getting more involved
+
+If you are participating in the xi-editor project, you may receive
+additional privileges:
+
+_Organization membership_: If you are regularly making contributions
+to a xi project, in any of the forms outlined above, we will be happy to
+add you to the xi-editor organization, which will give you the ability
+to do things like add labels to issues and view active projects.
+
+_Contributor_: If you are regularly making substantive contributions
+to a specific xi project, we will be happy to add you as a contributor
+to the repo in question. Contributors are encouraged to review and
+approve changes, respond to issues, and generally help to maintain
+the project in question.
+
+_Maintainer_: If you are making substantive contributions to multiple
+repos over an extended period, you are regularly reviewing the work of
+other contributors, and you are actively participating in planning and
+discussion, you may, (at the  discretion of @raphlinus) be invited to
+take on the role of _maintainer_. Maintainers are responsible for
+coordinating the general direction of the project, resolving
+architectural questions, and doing the day to day work of moving the
+project forward.

GUIDELINES

-nothign