Fixed a bug in the complex PVS generation which was causing recursive loop.
Move some of the settings out of RoomManager into Project Settings.
Allow PVS generation method to be selected from Project Settings, and control PVS logging.
The existing tracing routine for building the PVS was rather simple compared to the main portal tracing, and could not correctly cope with paths that went through multiple portals from room A to B, and as a result would sometimes miss room entries in the PVS resulting in too many culled rooms in these circumstances.
This PR adds an improved function that can cope with entering a room multiple times during a trace. As a result it has to take care of portal directions (to prevent going back on itself) in a similar, but not identical way to the main portal tracing routine, and internal rooms, to prevent recursive loops.
In some situations looking out from an internal room it was possible to look back into the portal into the internal room.
This PR fixes this by keeping a single item 'stack' record of the last external room, and preventing recursing into this room. This also makes tracing significantly more efficient out of internal rooms, as there is no need to trace the external room multiple times.
