Cycles: tweaks to properties and nodes

* 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.

intern/cycles/render/buffers.h

@@ -47,7 +47,7 @@ public:
 	~RenderBuffers();
 
 	void reset(Device *device, int width, int height);
-	float4 *copy_from_device(float exposure, int pass);
+	float4 *copy_from_device(float exposure, int sample);
 
 protected:
 	void device_free();