Graphical feature requests

[joevenzon]

Notes from a conversation on IRC with rufsketch1:
* bloom doesn't seem to work on GT240?
* motion blur still isn't reimplemented
* only one specular/reflection control, need support for a proper specular/shininess map
* support for dynamic environment maps on cars, but static environment maps for track geometry
* support for adjustment of ambient light, sun light values per track

Also another note to myself since he's talking about adding more normal maps:
* the normal mapping currently uses a dynamic tangent basis computation, which is kind of slow, and could easily be precomputed instead