First commit Tomaten-Tijd

This is my "poor man's" Pomodoro Technique timer. It's a very minimal
script for my personal use so I can experiment with the Pomodoro
Technique. There are plenty of apps supporting this, but guess what none
of them were written by me so I wrote another ;)

I'd only like to add an indicator the script is running and
make sure only one instance may run at the time. After these features have been added I
would consider Tomaten-Tijd feature complete.

I'm sharing this in the hope it may be useful to someone else.