Setup travis CI

[Vindaar]

Setup travis CI for the Nim modules in this repo. Would be the perfect use case for our installation tool, due to the dependencies.

[Vindaar]

Start. Writing. Tests.

• InGrid / FADC file, one example into tests, use the different read functions, check parsing expected results
• check layout of a full run H5 file after raw / after reco / after likelihood for datasets / attributes / groups

Bitten by these two heavily in the last days...

• perform all fits on some datasets to check if something broke
• ...

[Vindaar]

Instead we need to move over to Github actions and finally finish the CI & make sure the tests still pass (hint: they won't right now).