Optimizations to Ogre's default Terrain manager

Take a look at this thread and read the PDF. Some changes to the vertex format of the vertices leads to some impressive vertex buffer size reductions.

http://www.ogre3d.org/phpBB2/viewtopic.php?t=16922

Well PLSM2 already does, but if patch applied we could use new vertex type to reduce it a bit, if it works.