Rename ISceneManagerAdapter, do not build old SM.

 - ISceneManagerAdapter is responsible for managing terrain related
   data, therefore rename it to ITerrainAdapter.
 - Do not build EmberPagingLandscapeSceneManager.
Refactoring, change terrain intersection testing.

- Create scene manager for main menu directly in EmberOgre.
- Rename the scene manager and camera objects in EmberOgre.
- Introduce rayIntersects to ITerrainAdapter to check for ray
  collisions.
- Use rayIntersects instead of RaySceneQueries in AvatarTerrainCursor
  and in EntityWorldPickListener.