Window improvements

The window will now no longer set its position if fullscreen mode has
been specified.

During the initialization of the animator, Titania now polls the main
monitor's refresh rate; if the fps_limit config option is unset, this
will be used as the default, thus supporting 120Hz and 240Hz displays.

Additionally, the hook for the window resize event has been disabled,
pending investigation.  NEWT window events are processed "before"
firing, and insofar it does not appear necessary to manually dispatch
resize events to the renderer.