Screen To Gif 2.16

What's new in this version:

New:
- Added FFmpeg as an optional encoder for Apng
- Updated the German and Russian translations

Bug fixes:
- A message about a missing FFmpeg instance was not interactive
- When loading images, if those images were not in the correct format, the app would not encode properly as Apng
- There was an issue with one of the numerical input fields not working as expected (with numbers being typed)