Pympress

- Some packages were missing translation files
- Added cleanup of directories that pympress 1.5 RPMs left around (causing pympress to fail to start ater update, 194)
- Update the `gstreamer` backend to play videos for more stability (should work on all platforms provided gstreamer is installed)

Caused bugs in file watching (203) and media playing (197).

- fix some PDF links not working
- improve screensaver handling
- include compiled translation catalogs (.mo files) on pypi
- cleaner log files
- complete and correct various distribution metadata

- Support LibreOffice-style notes pages, after slides pages
- Add support for drawing on slides with various presets and an eraser preset
- Add command-line control of pympress, thanks to Gtk.Application single-instance ability
- Ensure file handles of closed files are released through early garbage collection
- Various improvements in binary (rpm / msi) releases
- Fix rendering bugs on scaled displays and with embedded fonts