Blender Git Loki

Render Branch: lamp falloff

* Change lamp falloff formula which was dist/(r^2 + dist) with dist
a user specified value, whereas the correct value is 1/(r^2). Now
it is 1/(r^2 + dist) with dist = 0 as the default.
* Deprecated the Lin/Quad weighted mode.
* Still more work needed to make sun/area/hemi work better with this,
results are too bright now.
* Also this gives quite harsh results when the lamp is near geometry,
perhaps because we are not using tonemapping by default.