Night theme / simple auto-solver

This adds 3 features to OpenSudoku:

1- a simple green-on-black "night" theme.
2- a setting to automatically update fill-notes after a change.
3- an option to auto-solve trivial moves ... this works with the fill-notes features by solving unambiguous single notes. A demo of it can be found at http://www.youtube.com/watch?v=v1yzLl6TK6Y -- Obviously the solver is just a little fun thing, not serious. It's a setting that I don't think people would activate all the time, if at all.

I wrote these changes back in 2010 and ported them to OpenSudoku 1.1.5