fix notehead bounding box

[rvilarl]

fixes #556

• noteheads of stavenotes are not preformatted.
• stavenot reset should use setstave to recalculate properly.

[rvilarl]

Test changed to use also StaveNotes, this one wouldfail without this PR (current first)

Differences due to StaveNote change (current first)

[sschmidTU]

All the comparison images look the exact same to me, is the difference so small?
Though generally it's always nice to fix the bounding boxes, we also noticed some inaccuracies there in OSMD.

[rvilarl]

@sschmidTU The first test, which was modified to use StaveNotes rather than NoteHeads crashes without the modification.
The last beam with rests in the middle is lower.
The 3 on the last image is very slightly lower.

[rvilarl]

By the way the bounding box calculation is not accurate but I did not go into that.