This milestone is preparing the way to the minimum viable product.

The improvements should be as follows:
Jest is implemented as a testing framework and some aspects of the app are tested with automated testing.

Scales must be shown correct, double sharps, correct distribution of C-D-E-F-G-A-B
Scales German notation must use B in stead of Hb

One custom scale can be created and shared.

The scales are mapped on the keyboard first note on the A-key , then on every key up to the *-key
Double sharps must be implemented in staff-module(score) and in sound module.

The octave can be shifted, resulting in tones being shown and sounding in the selected octave.

The note staff can be toggled on and off