Build type information on first use (load-time), instead of using a hardcoded list

--HG--
branch : dynamiccore2

src/modules/graphics/opengl/Canvas.cpp

@@ -88,6 +88,7 @@ static GLenum createMSAABuffer(int width, int height, int &samples, GLenum iform
 	return status;
 }
 
+love::Type Canvas::type(&Texture::type);
 Canvas *Canvas::current = nullptr;
 OpenGL::Viewport Canvas::systemViewport = OpenGL::Viewport();
 bool Canvas::screenHasSRGB = false;