#12 More minor Scales

[Christoph Eckert]

In the prefs, it is possible to set the scale to be
trained. Currently, only major scales can be
selected, so Major and natural minor scales are
trainable. This is possible because major and natural
minor use the same tones.

Unfortunately, there are two other minor scales
(harmonic minor and melodic minor) which do not use
the same tones as major, so these should also be
configurable in a later release.