Magic Cube

Bugfix.

Add 7x7 tutorials.

Tutorials for the 6x6

Move the main app to the 'J1M1' object creation mode, i.e. create them from the Json files and using the Dmesh fiels as well.

Make it possible for any app descending from the 'objectlib' to use any of the J0M0, J0M1, J1M0, J1M1 modes.

Remove ObjectType from a few moree places.

Remove dependancies on Firebase from objectlib.
Report such errors to the application via the Interface.

Progress with PuzzleTester app.

Fix for a rare crash.

new API to make is possible to adjust default scale factor in each TwistyObjectNode.
(and use it in Tutorials, where the object needs to be smaller)

Major change: separate the notion of a TwistyObject and its Node. Now,

1) the Node stays when we change objects (this makes transitions faster)
2) it's possible to just create an Object without adding it to the Screen (now app needs to explicitly create the Node and add it to its Screen itself)