Some improvements on key bindings

List of changes:
- do not automatically create default keys if they do not exist, when reading
  weechat.conf (let user do that if needed)
- add "/key missing": add missing keys using default keys (do not update or
  remove user keys),
- key "meta-s" moved from irc/jabber plugins to core
- improved output of /key (display number of keys)

src/plugins/irc/irc-server.c

@@ -2184,9 +2184,6 @@ irc_server_connect (struct t_irc_server *server)
         weechat_buffer_set (server->buffer, "display", "auto");
         
         weechat_bar_item_update ("buffer_name");
-        
-        weechat_buffer_set (server->buffer, "key_bind_meta-s",
-                            "/command irc /server switch");
     }
     
     if (!server->addresses_array)