[Bug-gnubg] Appearance changes

[Jon Kinsey]

I've just checked in some changes to the appearance preference dialog, 
mainly moving the preview from the notebook pages to a single preview.
This was to avoid 3d problems with the pixmap rendering which was also 
slow (unaccelerated).

What looks like a cosmetic change actually required quite a few changes, 
I took the chance to tidy some odds and ends up at the same time.  I've 
probably introduced a few bugs along the way...

When you add a new design some rough settings get put into the other 
dimension, I've also added an "update design" button.


I've managed to do everything that was on my todo list!  There's a whole 
bunch of "possible enhancements" that I've come across, I'm going to 
take a break for a few weeks before I start looking at these.

Jon