Touch extension and callbacks *DO NOT MERGE*

I have outlined the touch extension to take callbacks to process messages for Win32, but there are some issues. First, the extension system needs at least an initialization function for an extension where I can load the function pointers.

I also removed and reimplemented WindowResized as an installable callback that the graphics bridge no longer has to install if it don't want to. @sorlok I have tested on XLIB but not Mac, I am afraid this may break Mac again, but the purpose of this is that so I can implement future callbacks the right way without breaking other platforms; I should have done it this way the first time.