Final frontend interface

[WojciechPtas]

We should gather all the ideas for the compiler frontend and implement it, rahter sooner than later.

• [ ] Test the exacutable via python scripts (maybe ressurect fuzzing)
• [ ] Differ exit code depending on phase that is failing
• [x] #319
• [x] Make sure that --help is up to date
• [ ] Impl version and other funny infos
• [ ] Add flags/config to be read from file
• [x] Default output to file
• [ ] Fix error messages
• [ ] Unify logging