Poxy

- added arguments `--min-version` and `--squash-patches` for more control over `--git-tags` mode

- added multi-version mode argument `--git-tags`
- added colour to output

- added config option `main_page` (a.k.a. `USE_MDFILE_AS_MAINPAGE`)
- fixed searching for `CHANGELOG` too far up the directory heirarchy (now stops when a `.git` folder is encountered)

- added the use of `*` wildcards in `implementation_headers`

- fixed crash on Doxygen <= 1.8.17 (33) (tim-janik)

- fixed regression for Python <= 3.8 (32) (tim-janik)