[wpwfquhx] Black and white notes and keys

Modify music notation so that the white notes (formerly whole note and half note) correspond to the black keys, and the black notes (quarter note etc.) correspond to the white keys on a piano keyboard.

We invert colors because black notes have better contrast on a white page, and there are more white keys: make the common case better.

This note color is information redundant with key signature and accidentals, but is intended to aid sight reading.

Simplest way to do this is whole note and half note become notated as tied quarter notes.

Another way to do this, requiring less radical modification of notation, is simply to use more colors, e.g., no change in color for white keys and red notes for black keys.