Show measure number!

[martin-mueller]

[martin-mueller]

Problems:

• st3 api can only count measures for the whole files, usable:
  len(view.find_by_selector('constant.measure.end.braille'))
• must divide by staff count
  view.find_by_selector('sublimelinter.mark.error.staff.braille')
• must divide staff count by sections
  view.find_by_selector('meta.diff.section.braille')
• must count whole measure similes