Camera system changes

- Renamed Camera class to EditorCamera, to avoid future ambiguity with
CAM file cameras
- Changed SADXLVL2 to have SonicGLVL-style camera controls.
- Changed orbit mode to function more like MAX's camera orbit mode.
Merge branch 'master' of https://github.com/sonicretro/sa_tools

Conflicts:
	SAModel.Direct3D/Extensions.cs