Rename R_IsPointInSubsector to R_PointInSubsectorOrNull/Nil
The old name made it really easy to accidentally read R_IsPointInSubsector as R_PointInSubsector, and anyway it didn't even make sense...
The old name made it really easy to accidentally read R_IsPointInSubsector as R_PointInSubsector, and anyway it didn't even make sense...