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 is for tunes that are not part of the regular
Havoc session or dance repertoire.

Typically these tunes have either fallen out of popularity at sessions,
or are simply tunes that I like.