Canvases can now be used in SpriteBatches, ParticleSystems, and Meshes (resolves issue #782).

Canvases and Images are now subclasses of the new Texture class.
Added setTexture and getTexture methods for Meshes, ParticleSystems, and SpriteBatches (the old set/getImage methods are deprecated but not removed.)
Canvas texture coordinates are no longer flipped.

src/common/runtime.cpp

@@ -671,6 +671,7 @@ StringMap<Type, TYPE_MAX_ENUM>::Entry typeEntries[] =
 
 	// Graphics
 	{"Drawable", GRAPHICS_DRAWABLE_ID},
+	{"Texture", GRAPHICS_TEXTURE_ID},
 	{"Image", GRAPHICS_IMAGE_ID},
 	{"Quad", GRAPHICS_QUAD_ID},
 	{"Font", GRAPHICS_FONT_ID},