moved d_lightstylevalue into r_refdef.lightstyle

moved d_lightstylevalue into r_refdef.lightstyle
moved r_dlights into r_redef.lights and made it an array of pointers into cl_dlights to save memory and time
merged R_UpdateLights into CL_DecayLights and renamed it CL_UpdateLights
renamed R_RTLight_UpdateFromDLight to R_RTLight_Update and made it take only the dlight pointer
implemented cl_activedlights variable to prevent scanning whole MAX_DLIGHTS range every frame

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@5765 d7cf8633-e32d-0410-b094-e92efae38249