Irssi plugin to use messaging menu indicator (https://wiki.ubuntu.com/MessagingMenu).

Components:
* irssi: The IRC client.
* irssi_indicator_plugin.pl: The plugin for irssi.
* irssi_indicator.pm/irssi_indicator.so: Generated with SWIG, we use this library to comunicate between C and Perl.
* messaging_menu: Messaging menu indicator library.

irssi <=> irssi_indicator_plugin.pl <=> irssi_indicator.pm <=> irssi_indicator.so <=> messaging_menu