When adding source files to the _FILES variables conditionally
those are so far not being formatted or translated. Adding
these files at least to the EXCLUDED_FILES will fix this.
Replaces DOC_ONLY_FILES which served the same purpose but was
limited to documentation.
* Prevent warnings about required tools being unavailable
when tidy/coverage targets aren't desired anyways (eg.
when packaging)
* Do not automatically execute tidy check when packaging
in unclean environment
* Append Git revision and ID of latest commit
to version displayed via --help
* Can be turned off via option
* Has no effect if the source dir is not
a Git checkout or Git is not installed
* Implements
https://github.com/Martchus/tageditor/issues/13