[Gtkradiant] credits page

[Timothee Besset]

I have updated the credits page that is to be distributed with the
setups. Ideally we would use the same page on the web. I probably missed
some people, and there may be some erroneous things. Please check it and
send feedback. Specially on the web team, I would like a more complete
list.

http://www.gtkradiant.com/test/credits.html

TTimo

PS: Maj is still waiting on a small version of the new QER logo to put
on the splash screen for next GtkRadiant