Fully integrates CoglMaterial throughout the rest of Cogl

This glues CoglMaterial in as the fundamental way that Cogl describes how to
fill in geometry.

It adds cogl_set_source (), which is used to set the material which will be
used by all subsequent drawing functions

It adds cogl_set_source_texture as a convenience for setting up a default
material with a single texture layer, and cogl_set_source_color is now also
a convenience for setting up a material with a solid fill.

"drawing functions" include, cogl_rectangle, cogl_texture_rectangle,
cogl_texture_multiple_rectangles, cogl_texture_polygon (though the
cogl_texture_* funcs have been renamed; see below for details),
cogl_path_fill/stroke and cogl_vertex_buffer_draw*.

cogl_texture_rectangle, cogl_texture_multiple_rectangles and
cogl_texture_polygon no longer take a texture handle; instead the current
source material is referenced. The functions have also been renamed to:
cogl_rectangle_with_texture_coords, cogl_rectangles_with_texture_coords
and cogl_polygon respectivly.

Most code that previously did:
  cogl_texture_rectangle (tex_handle, x, y,...);
needs to be changed to now do:
  cogl_set_source_texture (tex_handle);
  cogl_rectangle_with_texture_coords (x, y,....);

In the less likely case where you were blending your source texture with a color
like:
  cogl_set_source_color4ub (r,g,b,a); /* where r,g,b,a isn't just white */
  cogl_texture_rectangle (tex_handle, x, y,...);
you will need your own material to do that:
  mat = cogl_material_new ();
  cogl_material_set_color4ub (r,g,b,a);
  cogl_material_set_layer (mat, 0, tex_handle));
  cogl_set_source_material (mat);

Code that uses the texture coordinates, 0, 0, 1, 1 don't need to use
cog_rectangle_with_texure_coords since these are the coordinates that
cogl_rectangle will use.

For cogl_texture_polygon; as well as dropping the texture handle, the
n_vertices and vertices arguments were transposed for consistency. So
code previously written as:
  cogl_texture_polygon (tex_handle, 3, verts, TRUE);
need to be written as:
  cogl_set_source_texture (tex_handle);
  cogl_polygon (verts, 3, TRUE);

All of the unit tests have been updated to now use the material API and
test-cogl-material has been renamed to test-cogl-multitexture since any
textured quad is now technically a test of CoglMaterial but this test
specifically creates a material with multiple texture layers.

Note: The GLES backend has not been updated yet; that will be done in a
following commit.

clutter/clutter-texture.c

@@ -635,22 +635,13 @@ clutter_texture_paint (ClutterActor *self)
   /* Paint will have translated us */
 #if USE_COGL_MATERIAL
   cogl_set_source (priv->material);
-
-  tex_coords[0] = 0;
-  tex_coords[1] = 0;
-  tex_coords[2] = t_w;
-  tex_coords[3] = t_h;
-  cogl_material_rectangle (0, 0,
-                           (float)(x_2 - x_1),
-			   (float)(y_2 - y_1),
-                           4,
-                           tex_coords);
 #else
-  cogl_texture_rectangle (priv->texture, 0, 0,
-                          (float)(x_2 - x_1),
-                          (float)(y_2 - y_1),
-                          0, 0, t_w, t_h);
+  cogl_set_source_texture (priv->texture);
 #endif
+  cogl_rectangle_with_texture_coords (0, 0,
+			              (float) (x_2 - x_1),
+			              (float) (y_2 - y_1),
+			              0, 0, t_w, t_h);
 }
 
 /*
@@ -769,6 +760,7 @@ clutter_texture_set_property (GObject      *object,
 	(texture, (CoglHandle) g_value_get_boxed (value));
       break;
 #if USE_COGL_MATERIAL
+    case PROP_COGL_MATERIAL:
       clutter_texture_set_cogl_material
         (texture, (CoglHandle) g_value_get_boxed (value));
       break;
@@ -2188,7 +2180,7 @@ on_fbo_source_size_change (GObject          *object,
       if (priv->filter_quality == CLUTTER_TEXTURE_QUALITY_HIGH)
         flags |= COGL_TEXTURE_AUTO_MIPMAP;
 
-      priv->fdo_texture =
+      priv->fbo_texture =
         cogl_texture_new_with_size (MAX (priv->width, 1),
 				    MAX (priv->height, 1),
 				    -1,