Add mode to overwrite strips on overlap instead of resolving overlap.
When overlap is created, 3 things can happen:
- On partial overlap, handles of overlapped strip are moved
- On complete overlap with smaller strip, overlapped strip is split
- On complete overlap with larger strip, overlapped strip is removed
This mode can be enabled in header.
Reviewed By: fsiddi, mano-wii
Differential Revision: https://developer.blender.org/D11805
59cd9c6da6