If ScriptStopStrategy hasn't been set to co-op in [XEngine] config, then continue to generate C# that is functionality identical to historical generation

This is to eliminate disruption until co-op termination has been well-tested.
In non co-op mode, XEngine will continue to load DLLs of the existing Script class and the new XEngineScript class.
Moving to co-op mode still requires existing script DLL deletion to force recompilation, either manually or by setting DeleteScriptsOnStartup = true for one run.
This change also means that scripts which fail to initialize do not still show up as running scripts.

OpenSim/Region/ScriptEngine/Interfaces/IScriptEngine.cs

@@ -78,6 +78,14 @@ namespace OpenSim.Region.ScriptEngine.Interfaces
         string ScriptEngineName { get; }
         string ScriptEnginePath { get; }
 
+        /// <summary>
+        /// Return the name of the class that will be used for all running scripts.
+        /// </summary>
+        /// <remarks>
+        /// Each class goes in its own assembly so we don't need to otherwise distinguish the class name.
+        /// </remarks>
+        string ScriptClassName { get; }
+
         /// <summary>
         /// Return the name of the base class that will be used for all running scripts.
         /// </summary>