Lighting-related block variables

[worktycho]

m_SpreadLightFallOff is how much light is lost when going through that block. Its a scale of 0 - 15 where 0 is no light lost and 15 which is completely opaque. Transparent blocks are 1 not 0 though. Those that aren't in the list get the default of 15. m_SpreadLightFallOff is not used outside of the Lighting engine. Everything else uses m_Transparent which is the more simple bool value of can you see through it.