Lightmass: multi-bounced sky lighting

[anonymous_user_4230003f]

I did extensive profiling on all the 4.18 Lightmass changes and my findings were ~5% faster builds in 4.18 with out of the box settings. If you get a chance to confirm the regression, post the repro in an answerhub and send me the link.

OK, I will make a thread tommorow in answerhub and send you the link. Maybe the problem is that I also change the baselightmass.ini.