missing commits from peter 20942, 21165, 21170, 21174, 21597
these files still need manual merging
source/blender/makesdna/DNA_sequence_types.h
source/blender/src/sequence.c
source/blender/src/seqeffects.c
source/blender/src/editseq.c
source/blender/include/BSE_sequence.h