SceneManager

- Return success/fail for public CreateRegion()
- Code cleanup
Misc code cleanup
Terrain updates

- Corrections to terrain map generation to optimise memory load,
particularly for large regions
- Additional terrain types
- Removal of incorrect settings for ‘Flatland’
- Code cleanup
Vehicle parameters

- Add serialization of vehicle parameters for OAR export & import
- Add vehicle parameters to region  ‘sim’ backup