Implements osForceSit(string avatar) & overload osForceSit(string avatar, string target)

Allows a script IN the target prim to force an avatar to sit on it using normal methods as if called by the client.

Overload method of osForceSit() to allow a script NOT in the target prim to force an avatar to sit on the target prim using normal methods as if called by the client.

This patch is based on previous work from
http://opensimulator.org/mantis/view.php?id=4492
and also includes the suggestions from justincc including change of threat level
Thank you Christos Lightling.

OpenSim/Region/ScriptEngine/Shared/Api/Implementation/OSSL_Api.cs

@@ -872,6 +872,59 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
 
             TeleportAgent(m_host.OwnerID.ToString(), regionX, regionY, position, lookat, true);
         }
+        ///<summary>
+        /// Allows a script IN the target prim to force an avatar to sit on it using normal methods
+        /// as if called by the client.
+        /// Silent fail if agent (or target if overloaded) not found.
+        /// Does work if passed key (or keys if overloaded).
+        /// </summary>
+        /// <param name="avatar"></param>
+        public void osForceSit(string avatar)
+        {
+            CheckThreatLevel(ThreatLevel.VeryHigh, "osForceSit");
+
+            m_host.AddScriptLPS(1);
+
+            ForceSit(avatar, m_host.UUID);
+        }
+        /// <summary>
+        /// Overload method of osForceSit(string avatar) to allow a script NOT in the target prim to force
+        /// an avatar to sit on the target prim using normal methods as if called by the client.
+        /// </summary>
+        /// <param name="avatar"></param>
+        /// <param name="target"></param>
+        public void osForceSit(string avatar, string target)
+        {
+            CheckThreatLevel(ThreatLevel.VeryHigh, "osForceSit");
+
+            m_host.AddScriptLPS(1);
+
+            UUID targetID = new UUID(target);
+            
+            ForceSit(avatar, targetID);
+
+ 
+        }
+
+        public void ForceSit(string avatar, UUID targetID)
+        {
+            UUID agentID; 
+
+            if (!UUID.TryParse(avatar, out agentID))
+                return;
+
+            ScenePresence presence = World.GetScenePresence(agentID);
+
+            SceneObjectPart part = World.GetSceneObjectPart(targetID);
+
+            if (presence != null &&
+                part != null &&
+                part.SitTargetAvatar == UUID.Zero)
+                presence.HandleAgentRequestSit(presence.ControllingClient,
+                    agentID,
+                    targetID,
+                    part.SitTargetPosition);
+        }
 
         // Functions that get information from the agent itself.
         //