* Add ability to destroy tickets

* Touch up configuration system.

* Add system-wide default configuration file for commands to run.

* I'm sure there are some memory leaks somewhere. Search and destroy.
  (valgrind!)

* Have some sort of visual change between the prompt for the password,
  entering your password, and succeeding.

* Better static documentation.

* Tooltips and other context-sensitive docs for the preferences window.

* Automatic ticket refresh when remaining time below (configurable)
  threshold and ticket is renewable and user is active

* Optional autologout when remaining time below (configurable)
  threshold (5min?)
