Lighting updates

[Rias]

- When in a completely dark room, any exits (compass directions or open portals) that lead to light areas will show under Obvious Exits. This should make it a bit easier on people who get stuck in dark areas and are fumbling around trying to find their way back out - particularly when going through a portal and getting stuck on the other side because you either forgot the portal name, or because for whatever reason the portal name is different on the other side.

- Due to the above, it is now possible to use the LOOK command in dark rooms instead of being simply told "You can't do that in complete darkness." Note: This only applies to LOOK by itself - it's still not possible to LOOK <target> in dark rooms.

- There's now a message for occupants of a room If an adjacent room was completely dark and has become lit, or was lit and has become completely dark.

- Fixed a bug that prevented the ability to GO <portal> in completely dark rooms.