Added preliminary IRegionModule interface.
Also have a work in progress way of Modules registering optional API methods (kind of like Apache optional functions). But there must be a cleaner/nicer way in c# of doing these than the current way.
Added three work in progress modules: ChatModule (simple handles in world chat, but by moving this to a module, we could support other types of chat modules, ie like a irc - opensim bridge module. ) , AvatarProfilesModule and XferModule.
Moved most of the code from Scene.ModifyTerrain() into the BasicTerrain library, as the start of trying to make that more modular.
Stopped Child agents showing up as part of the "show users" command.
PLEASE NOTE: that with this revision some prim related features may be broke for a while. (things like linking prims and the parcel prim count.)
Also this revision may not work on mono, but that will be fixed soon.
*Made the Parcel class its own file and moved the Parcel and LandManager into their own folder in Environment
*Some renaming might need to be done so the Parcel class doesn't have issues with the libsecondlife Parcel class, but Land doesn't seem right.
