Tilemap Stage3D version

it's a cobbled together version of the tilemap example; could use some major cleanup (also the uv coordinates are not set yet, but will use the same idea as in the bitmapdata based version http://wonderfl.net/c/vyIQ )

The idea is that from the camera matrix and projection we calculate the  start and end  coordinates where the tilemap should be drawn, the tilemap itself is a 3D object and the triangles are recalculated and uploaded every frame