[MusicXML] Ungraceful handling of a tie when next note is not the same pitch

During import of Music XML, when a tie is started on a note but the next note in the voice is not the same pitch, the tie is extended to the next appearance of a note that is the same pitch. This occurs even though this may be very many measures beyond with very many intervening notes.

This is a significant problem because Neuratron PhotoScore often incorrectly creates ties when it should create slurs. Among other cases, this happens when a note is slurred to a note that is on the same line or space but is a semitone above or below. Both Sibelius 6 and Finale 2012 handle PhotoScore's error by creating a tie that extends to the next note so it looks like a slur.