[Gtkradiant] setup fixes

[Timothee Besset]

I've commited fixes to the setup script, with a new bspc.exe binary and an 
improved setup.sh script. It will deal with Radiant's version tag as in 
include/version, will use it as the install name, binary name and shortcut 
in the start menu. Using a shell script to do find/replaces in the Is 
script might be crappy, but it's the only solution I've found..

As for next release .. early next week I will patch in Spog's stuff and 
^Fishman's new GenSurf code. We have a new splash screen coming courtesy of 
Maj too .. then .. well I think then we can release it :-)

TTimo