Bits and bobs

I set out to squash all of the compiler warnings, and I fixed all but one which is deep in the bowels of picomodel. There are several worthwhile fixes in here, too. We now have a window icon on Mac and Linux (this was broken), and it reflects the current branding too. Also I threw in "no_patch=true" for all of our idTech2 games, which streamlines the toolbars and preferences for them.