Blender Git Loki

Cycles: fix light strength mistmatch when clicking "use nodes".

Regarding merge status, there should be no build failures, but cycles may not
be enabled in your build, we are still solving:

* Windows: CUDA kernel compile at runtime is failing, probably will have to
do precompiled kernel again.
* Mac: scons is not building cycles yet.
* Linux doesn't have boost + openimageio libs available in lib/ yet, so it
requires manual install of those libs still.