Added Talea to rhythmmakertools.

The class is currently a stub.

The class will bundle these properties:

    * Talea.counts
    * Talea.denominator

The class will also house a significant amount of private code.

This will reduce the complexity of TaleaRhythmMaker considerably.

(And note, too, that a corresponding out-migration of private code from
IncisedRhythmMaker to InciseSpecifier will also be possible.)