Partial MR to consider some changes of !158

Hans proposed a series of improvements in !158 (closed) which may have been lost due to not-merging. Here is a partial MR to consider most of his ideas. The remaining good idea is to change ProcessSequence to directly use std::tuple.

changed milestone to %ICRC-2021

added Development ProcessAndSequence labels

added Ready for Code Review label

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• The MR is without WIP/Draft status
• Make sure the most recent CI jobs (config, quality, build_test_example) all run fine with no failures
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  • Check if the provided solution solves the Issue, discuss on gitlab
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  • Add MR label "Code Review Finished"
  • Rebase, if needed. If unclear: discuss!
    • rebased
    • not rebased

enabled an automatic merge when the pipeline for 7d62a723 succeeds

merged

mentioned in commit 90a5dcce