Timing function editor doesn't merge undos

[njx]

1. Open Quick Edit on a timing function
2. Drag one of the handles around
3. In the main document, undo a few times

Result: Each small change is recorded as an undo - they're not being merged.

[njx]

This is probably because of the change in CMv4 to the way edit and selection merges work. Either the same origin needs to be specified for setSelection(), or the edit and selection change should be wrapped in an operation.

Also, I'd suggest changing the origin to start with + rather than * - this makes it so only nearby changes in time are merged; I made that change recently to the color editor and I think it makes sense to be consistent.

[redmunds]

Marking Medium Priority as this was one of the original requirements.

[njx]

Fixed, closing.