Deleting annotations that were overlapping doesn't cause re-evaluation of stacking

[martinleopold]

For example:

• Reset to sample project
• In Track 5 ("Transcript") delete the 2nd annotation in 1st line ("You're the beginning and the end...")
• This should cause the track to collapse into one line, since there are no more overlaps. Instead it stays on two lines

Or:

• Reset to sample project
• In Track 5 ("Transcript") delete the annotation in 2nd line ("But the frivolous dot...")
• This should cause 2nd line to disappear, instead it stays