* cpu+memory: Open "gnome-system-monitor"
* disk: Open nautilus
* pulseaudio: Mute/unmute, open "pavucontrol" on right-click, raise/lower
volume on mouse wheel up/down
Pass the "output" object to the modules' constructor to allow them to
define their own callbacks.
Any user-provided callbacks take precedence and override those of the
module.
Add a new module "disk" that takes an optional parameter (the path) and
displays free & total disk space, along with the usage percentage.
Also, added Tunnel/VPN support to the themeing of the "net" module.
