Remove the legacy bridge.

Circe now fully uses the new irc.el API. The last remnants of
the Old IRC Interface have been swept away.

This creates a number of backwards-incompatible changes.

The whole message handler functionality is gone. Use the irc.el
event handlers instead.

All functions using the "nick user host" argument triple now take
"nick userhost" instead.

Also, the message option functionality was removed, and ignore/fool
is now handled by circe-display alone.

Fixes #124 and fixes #127

circe-lagmon.el

@@ -219,7 +219,7 @@ in the mode-line."
       (irc-handler-remove table "irc.ctcp.LAGMON"
                           'circe-lagmon--ctcp-lagmon-handler)
       (irc-handler-remove table "NICK" 'circe-lagmon--nick-handler))
-    (circe-set-display-handler "CTCP-LAGMON" nil)
+    (circe-set-display-handler "irc.ctcp.LAGMON" nil)
     (when circe-lagmon-timer
       (cancel-timer circe-lagmon-timer)
       (setq circe-lagmon-timer nil))
@@ -230,7 +230,7 @@ in the mode-line."
         (irc-handler-add table "irc.ctcp.LAGMON"
                          'circe-lagmon--ctcp-lagmon-handler)
         (irc-handler-add table "NICK" 'circe-lagmon--nick-handler))
-      (circe-set-display-handler "CTCP-LAGMON" 'circe-display-ignore)
+      (circe-set-display-handler "irc.ctcp.LAGMON" 'circe-display-ignore)
       (dolist (buffer (circe-server-buffers))
         (with-current-buffer buffer
           (setq circe-lagmon-server-lag nil)