* Passes renamed to samples
* Camera lens radius renamed to aperature size/blades/rotation
* Glass and fresnel nodes input is now index of refraction
* Glossy and velvet fresnel socket removed
* Mix/add closure node renamed to mix/add shader node
* Blend weight node added for shader mixing weights
There is some version patching code for reading existing files, but it's not
perfect, so shaders may work a bit different.
* Add alpha pass output, to use set Transparent option in Film panel.
* Add Holdout closure (OSL terminology), this is like the Sky option in the
internal renderer, objects with this closure show the background / zero
alpha.
* Add option to use Gaussian instead of Box pixel filter in the UI.
* Remove camera response curves for now, they don't really belong here in
the pipeline, should be moved to compositor.
* Output full float values for rendering now, previously was only byte precision.
* Add a patch from Thomas to get a preview passes option, but still disabled
because it isn't quite working right yet.
* CUDA: don't compile shader graph evaluation inline.
* Convert tabs to spaces in python files.
* auto/fixed threads option is used now, patch by Thomas.
* remove unused CUDA_LIBRARIES, library is dynamically loaded
* fix mesh XML export operator for API update
* kernel has shading nodes / textures disabled, amd/nvidia opencl
compilers choke on these, need to figure out how to avoid this
* works in cycles_test, not available as option in blender yet
* kernel compiles and runs with opencl 1.1 from intel/amd/nvidia
