Port of tgstation/tgstation#26975.
Changes the lighting engine to apply lighting changes in one step using stored lum value differences instead of two steps (remove_lum, add_lum).
Seems to show a speedup in lighting updates as well as a reduction in server memory usage due to aggressive freeing of unneeded lists.
Lighting overlays also default to fullbright instead of fulldark so movable area transitions look less strange.
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