- Add Dispose method to IRegionDataStore

- Add necessary dummy Dispose-methods where they are missing
- Implement the SQLite Dispose-methods
(currently only used for unit tests, in the next commit)

OpenSim/Data/SQLite/SQLiteAssetData.cs

@@ -56,7 +56,14 @@ namespace OpenSim.Data.SQLite
 
         private SqliteConnection m_conn;
 
-        override public void Dispose() { }
+        override public void Dispose()
+        {
+            if (m_conn != null)
+            {
+                m_conn.Close();
+                m_conn = null;
+            }
+        }
 
         /// <summary>
         /// <list type="bullet">