add macro for creating chromatic keyboard

[walterbender]

It would be familiar to many people to see a keyboard that spans an octave but includes black and white keys in the music keyboard widget.

It can be done by using 10 individual pitch blocks, but that is tedious. An easier way is to use the step pitch block while in "chromatic" mode as per the figure.

It would be nice to add a new macro for this and put it on the widget keyboard, similar to what we do for G and C major and the Phrase Maker.

[Jasbir96]

GCI marked bugs reserved for GCI or anyone could contribute on these

[walterbender]

Feel free to take on any open issue.