[Gtkradiant] shift+b functionality in Gtk

[Roger Cordes]

I love shift+b to do a "fit" operation as much as the next mapper, but I'm
starting to think that it doesn't really need to open the surface inspector
window as well.  We already have a keystroke to get the surface inspector
open, and I think it would be nice if shift+b could be "streamlined," let it
be allowed to perform its operation without cluttering up the screen and
requiring you to take the time to close a window when finished.

Roger