Cycles:

* 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.

intern/cycles/render/mesh.cpp

@@ -392,7 +392,7 @@ void MeshManager::device_update_attributes(Device *device, DeviceScene *dscene,
 	progress.set_status("Updating Mesh", "Computing attributes");
 
 	/* gather per mesh requested attributes. as meshes may have multiple
-	 * shaders assigned, this merged the requested attributes that have
+	 * shaders assigned, this merges the requested attributes that have
 	 * been set per shader by the shader manager */
 	vector<AttributeRequestSet> mesh_attributes(scene->meshes.size());