Update to version 5.5.25

- Upgraded to FFMpeg 4.4
- Upgraded to OpenJDK 16.0.2
- Fixed result chapters have slightly wrong duration on some input files
- Fixed artwork from previous conversion being added to next conversation if artwork scan process did not complete on time
- Fixed missing chapters split from context menu
- Fixed output split by chapters, which was temporary broken
- Fixed book number was staying from previous conversion
- Added feature to remove artwork and "exactly same" artwork won't be added again if found during current scan.
- Some rework to architecture to allow artwork fix