Add Firebase Crashlytics.
Move to AndroidX, target API level 29.
Minor tweaks to the 'Prev' buton in Solving state;Relax requirements in the Manifest - now only 'android.hardware.faketouch' supporting device is required, i.e. something that supports basic point-click-drag-unclick. No need for full 'android.hardware.touchscreen' thing with its multitouch silliness.
Minor
Improve the upper_text.
Skeleton of a new dialog: High Scores
New module: Rubik App. Initial commit.