[trunk] tremolo cannot be added
Steps to reproduce:
1) create new score (4/4 time)
2) add two minims (1/2 notes) into the first bar.
3) drag a tremolo symbol onto the first note.
1) both notes change to whole notes
2) the tremolo is drawn somewhere in between them
The wrong symbol is drawn on top of the first note. The note values don't change.
May be related to issue #14836: [Trunk] Tremolo appear with one stroke under each note