Don't use SetScalingResolution when loading fonts

This fixes LoadTTF() calling into CGraphicsContext and setting state (in particular, setting the scaling resolution and resetting the origin and camera).  All it needs is the scale factors - it doesn't need to set state at all.  Doing so means it can't be done during routines which rely on that state (e.g. from a control during Process() or Render()).

This was noticed during the look into weird UI during text based sub rendering when the video is running in the background via CGUIVideoControl.

More work needed to fix that properly.