encoder: fix transcoding of VOB files

Add a check in the timeout to detect EOS or locks when the muxer
does not push the EOS event
Use a custom non linear editor instead of gnonlin
Handle video editor errors correctly
Rework tagger UI to make it fit better in the screen
encoder: set limits to queues in time for audio and video
Update video editor test utils
editor: fix segfault with long titles
Fix some leaks
Make plays description shorter
Improve memory management a but for the stats GUI

Release pixbufs as soon as they are no longuer needed
nle: let audiorate fill the audio silence gaps correctly
Use smaller images for the position tagging backgrounds
Add a new encoding quality
Use bitrates for video encoders
Bump release 0.20.0
Fix segfault in coordinates migration
WIP
WIP