Change the IScriptApi back to it's original form, removing XEngine

specific additions that should not have been there in the first place.
Sleeping and time measurement are now completely internal to XEngine

OpenSim/Region/ScriptEngine/Interfaces/IScriptInstance.cs

@@ -29,6 +29,7 @@ using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Threading;
+using System.Diagnostics;
 using OpenMetaverse;
 using log4net;
 using OpenSim.Framework;
@@ -163,6 +164,9 @@ namespace OpenSim.Region.ScriptEngine.Interfaces
         void ClearQueue();
         int StartParam { get; set; }
 
+        WaitHandle CoopWaitHandle { get; }
+        Stopwatch ExecutionTimer { get; }
+
         void RemoveState();
 
         void Init();