Opening a score with minimum empty measure for mmRest = 0 causes hang

Create a score with multimeasure rests and set minimum empty measure to 0 in MuseScore 1.3. Open in MuseScore ef3a7da47c

->Hang

It doesn't make sense to make this value 0. We need to change the UI to not allow 0 and make sure it's > 0 at import time.