- Added per-actor teleport fog modifications.

- New properties include TeleFogSourceType and TeleFogDestType.
- TeleFogSourceType is the fog left behind where the actor teleported away from.
- TeleFogDestType is the fog the actor sees when it arrives at its destination.
- Added A_SetTeleFog(oldpos,newpos) -- oldpos sets TeleFogSourceType, newpos sets TeleFogDestType.