Use std. vertex data for unmodified RasterNodes.
Minor optimization.
Merge pull request #543 from libavg/features/reuse_vertex_array

Reuse vertex data.

Add a default SubVertexArray that is used when a RasterNode just has a unit quad as vertex data. avg_checkspeed.py shows around a 10% speed increase.
Updated VideoDecoder with abstract method registerTextures( MCTexturePtr pTextures[4] )

Implemented the code in SyncVideoDecoder and created a fake stub in AsyncVideoDecoder

Current bug :

When calling registerTextures() MCTexture.cpp throws an assert error, because the current Texture
can't be found in the stack of Textures. In my opinion the textures should be available before
startDecoding is called, but i believe it is only available in the Render methods of the nodes.
Merge remote-tracking branch 'upstream/master'