It is now possible to use module interfaces without referencing Scene.
Place those interfaces in OpenSim/Region/Interfaces. They may not
use any refs from OpenSim.Region.Environment as parameters.
This resolves a circular library ref introduced in r5949
* Each module directory is currently inside one of the following category folders: Agent (Anything relating to do with Client<->Server communications.), Avatar (Anything to do with the avatar or presence inworld), Framework (Classes modules can use), Grid (Grid traffic, new OGS2 grid comms), Scripting (Scripting functions, etc), World (The enrivonment/scene, IE Sun/Tree modules.)
* This should be moved into a seperate project file.