Change Cvar_Cycle_f to use Q_atof to be consistent with other cvar code. Q_atof("0.3"), a float, does not == atof("0.3"), a double.
Fixes "cycle r_wateralpha 0.3 0.6 1" not working reported by AAS.

git-svn-id: svn://svn.code.sf.net/p/quakespasm/code/trunk/quakespasm@969 af15c1b1-3010-417e-b628-4374ebc0bcbd
Fence texture support on brush models, e.g. for rmqdemo2 e1m6rq.bsp. Based on Baker's implementation in Fitz Mark V. Consistent with Fitz Mark V, RMQEngine, FTEQW rendering.
Not implemented for world polys (afaik it's useless for world polys) but could be added if needed.

git-svn-id: svn://svn.code.sf.net/p/quakespasm/code/trunk/quakespasm@970 af15c1b1-3010-417e-b628-4374ebc0bcbd