3.51.0

• 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