Sometimes, when moving strip with 2 input effect attached and causing
strip overlap, this overlap is resolved incorrectly - too big offset
is applied. This is because effects are not taken into consideration
when "shuffeling" to resolve overlap.
To fix usual cases (transitions), overlap between strip and it's effect
is considered to be impossible.
There are edge cases, but these would be much more complicated to
implement and could have negative impact on performance.
Reviewed By: ISS
Differential Revision: https://developer.blender.org/D14578
502f3debf9