make interaction counter conform with output format
three points:
- for multiple showers the interaction counter writes two numpy files directly in the main corsika output directory. Should go in subdir
interaction-counter
or something. Otherwise making a large number of showers gets messy. - does it really have to be numpy binary files? can't we just write yaml? Making it convenient to read is the job of the IO Library..
- shouldn't it be optional? Or at least configurable. if I want 100k proton showers at 1 TeV I don't want 200k numpy files..