More abcfield.py updates and mark it Python 3. - Move title fixups into Python. - Move key display name expansion into Python. - Add Dottes-specific header continuation line format. None of the usual tools appears to support the official +: continuation.

This book provides the dots for the music to all the dances
performed by Cry Havoc. The name of the dance is given as the tune title.
If the name of the tune differs from the name of the dance, the tune
name is given in the subtitle.