same as v3.51.0 but with some critical bugfixes
- add keyboard shortcuts for align segments to keyframes and shift segment times
- implement play/loop only current segment #574
- improve cleanup after export (and remember settings) #1425
- improve concat output filename extension handling
- file opened: add "concat with currently opened file" option
- improve animations and implement reduced motion #1410
- dim segment colors in invert mode to make it more clear
- dependency and build system upgrades