Distorted Android

Change the Postprocessing effects: separate the radius and the halo.
Reason: we needed a way to specify the size of the halo around a postprocessed object; before it was automatically (and not very correctly) computed from the radius - before we knew the size of the object's bounding box, so this automatic computation was possible. Now we're removing the MashBase.getBounding(0 API, so the size of the halo has to be explicitly given by the user. This way is more correct anyway and gives the user more control (as the Multiblur app proves!)...

Move to AndroidX, target API level 29.

Dynamics App: add checking a Dynamic4D.

Add the 'convexity' param to Dynamics and the Dynamic app.

Improve the Dynamic app.

Dynamic App: add Toast.

Minor improvements in the Dynamics.

1. Change the API of Dynamic: split makeNowRunFor into two separate 'setDuration' and 'resetToBeginning'
2. Major changes to the 'Dynamic' app so that we can check more about the Dynamics.

Turn the Rubik app into a MemoryTest.

Rubk App: changes in the UI