Cycles Hair: Two basic bair shaders added

A new hair bsdf node, with two closure options, is added. These closures allow the generation of the reflective and transmission components of hair. The node allows control of the highlight colour, roughness and angular shift.

Llimitations include:
-No glint or fresnel adjustments.
-The 'offset' is un-used when triangle primitives are used.

intern/cycles/kernel/osl/osl_shader.cpp

@@ -180,6 +180,10 @@ static void flatten_surface_closure_tree(ShaderData *sd, int path_flag,
 					sc.data1 = bsdf->sc.data1;
 					sc.prim = bsdf->sc.prim;
 
+#ifdef __HAIR__
+					sc.offset = bsdf->sc.offset;
+#endif
+
 					/* add */
 					if(sc.sample_weight > 1e-5f && sd->num_closure < MAX_CLOSURE) {
 						sd->closure[sd->num_closure++] = sc;