try to manage lua memory leak prevention in a way thats safer from re-entrancy during finalization thread

BizHawk.Client.EmuHawk/tools/Lua/Libraries/EmuLuaLibrary.cs

@@ -159,6 +159,11 @@ namespace BizHawk.Client.EmuHawk
 			EventsLibrary.CurrentThread = script;
 			_currThread = script;
 			var execResult = script.Resume(0);
+
+			_lua.RunScheduledDisposes();
+			//not sure how this is going to work out, so do this too
+			script.RunScheduledDisposes();
+
 			_currThread = null;
 			var result = new ResumeResult();
 			if (execResult == 0)

LuaInterface/LuaInterface/Lua.cs

@@ -959,6 +959,26 @@ namespace LuaInterface
 
       #endregion
 
+			List<int> scheduledDisposes = new List<int>();
+
+		internal void ScheduleDispose(int reference)
+		{	
+			//TODO - theres a race condition here, see comment elsewhere
+			lock (scheduledDisposes)
+				scheduledDisposes.Add(reference);
+		}
+
+		public void RunScheduledDisposes()
+		{
+			//TODO - theres a race condition here, in case GC happens during this method
+			lock (scheduledDisposes)
+			{
+				foreach (var item in scheduledDisposes)
+					dispose(item);
+				scheduledDisposes.Clear();
+			}
+		}
+
 		internal void dispose(int reference) 
 		{
             if (luaState != IntPtr.Zero) //Fix submitted by Qingrui Li

LuaInterface/LuaInterface/LuaBase.cs

@@ -16,7 +16,7 @@ namespace LuaInterface
         ~LuaBase()
         {
             //Dispose(false);
-					Dispose(true); //zero 28-feb-2014 - fix memory leak?
+					Dispose(true); //zero 28-feb-2015 - fix memory leak?
         }
 
         public void Dispose()
@@ -31,8 +31,8 @@ namespace LuaInterface
             {
                 if (disposeManagedResources)
                 {
-                    if (_Reference != 0)
+									if (_Reference != 0 && _Interpreter != null) 
-                        _Interpreter.dispose(_Reference);
+                        _Interpreter.ScheduleDispose(_Reference);
                 }
                 _Interpreter = null;
                 _Disposed = true;