Extension Mechanism Cleanup

- Cleaned up existing extension debris, in anticipation of the new mechanisms to
  be included in future releases.  This includes install/uninstall and a full
  set of triggers.

src/Context.cpp

@@ -502,7 +502,7 @@ bool Context::verbose (const std::string& token)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// This needs to be taken out and shot, as soon as Lua extensions will allow.
+// This needs to be taken out and shot, as soon as hooks will allow.
 void Context::shadow ()
 {
   std::string file_name = config.get ("shadow.file");