Initial implementation of a Range element to display a tune range
Draw line from note centre to note centre
Add support for (editable) accidentals for top and bottom note heads.

Add "Update Range" button in Inspector.
Rename to Part Range
Renamed element to "Ambitus"
Moved dragable symbol from master palette's "Note heads" sectin to "Lines" section.
Merge pull request #567 from mgavioli/part_range_element

A new element for part range indication