Mantis#1591. Thank you graciously, Sempuki for a patch that:

Currently module loading is done ad-hoc. I propose creating a simple 
loader class that leverages Mono.Addins (and perhaps the new .NET 
addins when they become available in mono). Attached is a basic 
patch for review that compiles into HEAD, but doesn't yet replace 
any existing ad-hoc loaders.

OpenSim/Data/AssetDataBase.cs

@@ -42,5 +42,6 @@ namespace OpenSim.Data
         public abstract string Name { get; }
         public abstract void Initialise(string connect);
         public abstract void Initialise();
+        public abstract void Dispose();
     }
 }