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/Framework/Servers/OSHttpRequestPump.cs

@@ -58,4 +58,4 @@ namespace OpenSim.Framework.Servers
             return pumps;
         }
     }
-}
+}