Echo: wrap echo() for the XML-RPC server

this serves as a good example of how to reuse code for the XML-RPC
interface. we wrap it for convenience, so that all that needs to be
supplied to the web service method is the message to echo. of course,
other modules can wrap things how they feel the need to, even adding
authentication, i guess, if they wanted

note that it doesn't unregister the XML-RPC method. for starters, i
didn't add an unregister to DrBotIRC, so it can't, and secondly, it
looks like reregistering overwrites the old one. this hasn't been
extensively tested but that's what i'm seeing

modules/Echo.py

@@ -26,11 +26,27 @@ class Echo(Module):
     def register_handlers(self):
         """Hook handler functions into the IRC library."""
 
+        # register IRC regex handlers
         self.irc.add_global_regex_handler('pubmsg', r'^!echo\s+(.*)$',
                                           self.echo)
         self.irc.add_global_regex_handler('privmsg', r'^!echo\s+(.*)$',
                                           self.echo)
 
+        # register XML-RPC handlers
+        def echo_wrap(msg):
+            """Get back the sent message.
+
+            Args:
+                msg     the message to get returned
+
+            Returns:
+                msg
+
+            """
+
+            return self.echo(None, None, None, False, (msg,))
+        self.irc.xmlrpc_register_function(echo_wrap, 'echo')
+
     def unregister_handlers(self):
         """Unhook handler functions from the IRC library."""