Delete of global time signature after local causes corruption
GIT commit: 22b2c66
1) score in 4/4
2) ctrl+drag (local) 6/8 to measure 2
3) drag (global) 2/4 to measure 3
4) optional add notes to measure 3
5) select the 3/4
Result: corruption. Specifics differ according to whether you entered notes at step 4 or not. It's actually two different bugs. If you do enter notes, we should have prevented the deletion, but the detection code misses that case because of a quirk in how the time signagtures is deleted (we delete the segment but not the individual time signatures). The second is because we get the measure rest durations wrong when rewriting. Because of the way adding versus deleting time signatures is implemented, the rewriting code can't get both right when local time signatures are involved. It's one or the other. Adding works already, so it is easier to fix things up in cmdRemoveTimeSig().