[Gtkradiant] credits page

[Leonardo Zide]

> 
> 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.

  Looks good but you might have to remove Loki's name in the future if 
I decide to claim ownership of the code I wrote.

Leonardo