allow for Inventory database source to be specified in main

configs.  This works with sqlite and nhibernate backends, and
stays with default seperate ini files for mysql and mssql until
someone writes those.

OpenSim/Data/MySQL/MySQLInventoryData.cs

@@ -51,6 +51,12 @@ namespace OpenSim.Data.MySQL
         /// <summary>
         /// Loads and initialises this database plugin
         /// </summary>
+        public void Initialise(string connect)
+        {
+            // TODO: actually use the provided connect string
+            Initialise();
+        }
+
         public void Initialise()
         {
             IniFile GridDataMySqlFile = new IniFile("mysql_connection.ini");