* app/edit_selection.c: Finally moved selections snap to the
   guides again. Layer moves are slightly faster than before, if no
   guides are present.

 * app/gdisplay.c
 * app/gdisplay.h
 * app/gdisplayP.h: Use doubles for snap_to_point. Less rounding
   makes the result much better on low resolution. If it snaps, the
   result should be exactly the guide in almost all cases now. Only
   at very low resolutions, you may end up with an error of 1 pixel.
   Some code cleanup while I was on it... Fixes bug #2353.


--Sven