Cycles: per-BSDF normal input and new Bump node.

Each BSDF node now has a Normal input, which can be used to set a custom normal
for the BSDF, for example if you want to have only bump on one of the layers in
a multilayer material.

The Bump node can be used to generate a normal from a scalar value, the same as
what happens when you connect a scalar value to the displacement output.

Documentation has been updated with the latest changes:
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes

Patch by Agustin Benavidez, some implementation tweaks by me.

intern/cycles/blender/blender_shader.cpp

@@ -402,6 +402,10 @@ static ShaderNode *add_node(BL::BlendData b_data, BL::Scene b_scene, ShaderGraph
 			node = new ParticleInfoNode();
 			break;
 		}
+		case BL::ShaderNode::type_BUMP: {
+			node = new BumpNode();
+			break;
+		}
 		case BL::ShaderNode::type_TEX_IMAGE: {
 			BL::ShaderNodeTexImage b_image_node(b_node);
 			BL::Image b_image(b_image_node.image());