changes:
SSlighting is now FIFO - lights are processed in the order they are received instead of by whatever one was queued most recently.
Instant lighting updates now check CURRENT_TICKLIMIT instead of ITL. ITL has been removed due to it no longer being used.
SSlighting will no longer double-process lighting datums that have already been processed by instant lighting.
Instant/Intelligent lighting updates can now be disabled via. compile-time define.
Sunlight should no longer shine indoors.
Directional lighting now properly updates on direction changes again.
/datum/light_source/novis has been renamed to /datum/light_source/sunlight.
More lighting microoptimizations.
Converted two storage lists to be lazy.
