works with NULL worldmodel

works with NULL worldmodel
fixed overbright lighting!  (light flickering is now smooth and everything)
added r_editlights_rtlightssizescale and r_editlights_rtlightscolorscale which scale light properties when loading as well as saving (to undo the change - this can be exploited to modify all lights in the level)
reduced used area of attenuation texture a little to ensure black edges
changed defaults for attenuation texture settings and rtlights sizescale/colorscale to greatly improve performance while still looking good
now defaults to no fake bumpmapping on walls (saves texture memory and looks better to me)

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@2695 d7cf8633-e32d-0410-b094-e92efae38249