They are not automatically unloaded when unloading the model!

Redesigns, deletes and renames

Also noted authors propertly on contributed examples

- Renamed Begin3dMode() --> BeginMode3D()
- Renamed Begin2dMode() --> BeginMode2D()
- Renamed End3dMode() --> EndMode3D()
- Renamed End2dMode() --> EndMode2D()

Could correct possible issues on OpenGL 1.1