Check/fix tsv files to enable preview

[dweindl]

GitHub offers a nice tsv table preview, but this only works for well-behaved files. For example, all rows need to have the same number of columns. This is not always the case. See, for example, https://github.com/Benchmarking-Initiative/Benchmark-Models-PEtab/blob/master/Benchmark-Models/Schwen_PONE2014/parameters_Schwen_PONE2014.tsv:

This probably happens during manual modification of tsv files in some IDEs that remove trailing whitespace. We should add a pre-commit check for proper tsv.