Mesh Batch Cache: get rid of the ORCO VBO data, and reconstruct it in shader.

With only one MADD instruction we recover the orco data and reduce both the storage and the fetching cost of an attrib layer.

source/blender/blenlib/intern/math_vector_inline.c

@@ -658,6 +658,14 @@ MINLINE void invert_v2(float r[2])
 	r[1] = 1.0f / r[1];
 }
 
+MINLINE void invert_v3(float r[3])
+{
+	BLI_assert(!ELEM(0.0f, r[0], r[1], r[2]));
+	r[0] = 1.0f / r[0];
+	r[1] = 1.0f / r[1];
+	r[2] = 1.0f / r[2];
+}
+
 MINLINE void abs_v2(float r[2])
 {
 	r[0] = fabsf(r[0]);