Based on !1572 (merged). You know the drill by now.
This branch adapts all the linedef types that involve sector and plane lighting to UDMF:
lightfloor
and lightceiling
fields. By default, these values are relative to the sector's light level (or if the surface is affected by a shadowcasting FOF, relative to that). If the lightfloorabsolute
/lightceilingabsolute
flag is set, they're absolute values instead.