Tutorial should be moved to GAScripted

[HeliumAnt]

The current tutorial is partially hardcoded in the main sources.

It should really be rewritten to a GAScripted rather than having it's own dedicated Activity type.

Currently might not be possible due to the background screens (They're being drawn directly to the terrain color layer). Though that should be resolved with gpu primitives since that adds depth support, meaning the screens could be drawn as BitmapPrimitives in the background.