unwrapping pixmap operations. This makes sure the accelerated code gets
    invoked for pixmaps
Add pixmap migration support to kaa. Can't quite automatically migrate
    pixmaps off-screen, but soon we will. Can kick objects out of video
    memory. Move per-screen linked list pointers to pixmap private. Wrap
    Composite in preparation for migrating pixmaps. Have kasync ignore
    drawable type so that pixmaps trigger sync Add KdOffscreenFini to
    cleanup on server reset. Switch off screen area to have only a 'save'
    function; moving objects to off screen memory is done by saving then
    freeing the area.