basiconly lighting subsystem bifurcation flag

engine: creates and exposes a basicOnly flag, as well as early outs in relevant spots.

script: the rest of the basicoly denotations from the prior PR

immediate purpose: The basiconly flag referenced in https://github.com/GarageGames/Torque3D/pull/858

long term impact: strictly speaking, this one is only of true beneficial use for deferred shading.

Again, used to denote rendering objects which bypass the higher order lighting subsystems.