Stream.noteElementFromScaledX(): handle note overlaps

[vanderstel]

Background

Stream.noteElementFromScaledX() returns a note n from the stream whose leftmost x position (n.x) and rightmost x position (n.x + n.width) are within allowablePixels of the given x position. If no note falls within this range, we select the note whose leftmost and rightmost x positions are nearest to x.

Problem

It is possible for a note's rightmost x position to overlap with the next note's leftmost position. If n1 ends at 123 and n2 begins at 120, then an x value of 121 will return n2, but 122 will return n1!

Solution

The current PR fixes this issue by truncating note widths so that n1 never ends after n2 begins.

[mscuthbert]

Perfect. Thank you!