Part two of Darok's Bullet physics plugin: added the actual plugin, although haven't added the project to prebuild.xml yet.

Also might have messed up some of the SVN properties on some of the folders, so if the cleaning lady has to come in again, I just hope she doesn't moan.

OpenSim/Region/Application/OpenSimMain.cs

@@ -373,6 +373,11 @@ namespace OpenSim
                     this.m_physicsEngine = "OpenDynamicsEngine";
                     ScenePresence.PhysicsEngineFlying = true;
                     break;
+
+                case "BulletXEngine":
+                    this.m_physicsEngine = "BulletXEngine";
+                    ScenePresence.PhysicsEngineFlying = true;
+                    break;
             }
 
             configData.Commit();