Improved CountDown timer

- Improved configuration of the notification area (size and transparency)
- Added optional icons in the menubar to start, pause and end the time,
  and notify of remaining time
- It is now able to deal with suspending the laptop during the timer
  i.e. time runs in "user" time, not "computer running" time
- added hotkeys
  - able to call timer again with last period
  - or set new period