Enables script access to the per object dynamic attributes through the JsonStore

script functions. Adds JsonAttachObjectStore to associate a store identifier with
an object (scripts can only access the store in their host object, this could be
extended but isn't necessary for now).

Note this opens a method to the DAMap OSDMap. This will be removed later, but
greatly simplifies the code for now.

The JsonStore and these scripts are disabled by default.

OpenSim/Framework/DAMap.cs

@@ -73,6 +73,14 @@ namespace OpenSim.Framework
                 m_map = (OSDMap)OSDParser.DeserializeLLSDXml(rawXml);         
         }
         
+        // WARNING: this is temporary for experimentation only, it will be removed!!!!
+        public OSDMap TopLevelMap
+        {
+            get { return m_map; }
+            set { m_map = value; }
+        }
+        
+
         public void ReadXml(XmlReader reader)
         { 
             ReadXml(reader.ReadInnerXml());