Use Ogre 1.9

 - OverlaySystem is now a component, add to build and initialize it in OgreSetup
 - Scene Managers can retrieve the OverlaySystem from OgreSetup and
   register it with themselves to show overlays.
 - Add some implemented methods due to Ogre interface changes.
 - Purge includes of OgreProgressiveMesh since it was removed.
 - TODO: use QueuedProgressiveMeshGenerator from Ogre. Current state
   throws some cast exceptions in the background.