Distorted Android

Avoid a crash on exiting MessageSender

Minor: deal with IntelliJ warnings

minor

Important bugfix in the vertex shader: there was division by 0 in case Center point was on the edge of the Object, resulting in some vertices being shot into outer space.

Vertex3D almost finished - there's still a problem when parts of Cubes get culled if the Object gets Deformed or Distorted to the left (curiously only the 'left' direction seems to trigger this!)

Cleanup, consistent variable names, minor details.

Further progress with SenderThread: make it possible to actually exit the thread on app exit.

Major: the MessageSender thread used to be running all the time in a tight loop!!

Additional Javadoc stuff.

- Javadoc for EffectNames
- make Matrix effects consistent with the rest (center of effect as last parameter!)
- bugfix for yesterday's bugfix (we only want to send 'EFFECT_REMOVED' messages if it was really the Application that called 'abortAll' and not when we are cleaning up everything)