Implement Array, Cubemap, and Volume texture types (issue #1111).

- Add love.graphics.newArrayImage, newCubeImage, and newVolumeImage.
- Add love.graphics.newCanvas(w, h, layers) and newCanvas(w, h, layers, settings). Add ‘type’ field to the settings table of newCanvas.

- Add new love.graphics.setCanvas variants: setCanvas(canvas, slice), and setCanvas(canvastable) where canvastable is in the format: {{canvas1, layer=2}, {canvas2, face=5}}

- Add Texture:getTextureType, getDepth, getLayerCount, getMipmapCount, and getFormat.

- Remove Image:getData and Image:refresh.
- Add Image:replacePixels(imagedata [, slice] [, mipmap]).

- Update Canvas:newImageData to accept a slice argument.

- Add love.image.newCubeFaces(imagedata).

--HG--
branch : minor

src/modules/image/wrap_Image.cpp

@@ -122,12 +122,23 @@ int w_isCompressed(lua_State *L)
 	return 1;
 }
 
+int w_newCubeFaces(lua_State *L)
+{
+	ImageData *id = luax_checkimagedata(L, 1);
+	std::vector<StrongRef<ImageData>> faces;
+	luax_catchexcept(L, [&](){ faces = instance()->newCubeFaces(id); });
+	for (auto face : faces)
+		luax_pushtype(L, face);
+	return (int) faces.size();
+}
+
 // List of functions to wrap.
 static const luaL_Reg functions[] =
 {
 	{ "newImageData",  w_newImageData },
 	{ "newCompressedData", w_newCompressedData },
 	{ "isCompressed", w_isCompressed },
+	{ "newCubeFaces", w_newCubeFaces },
 	{ 0, 0 }
 };