Using [jsspencer/pomo](https://github.com/jsspencer/pomo) as the timer
of choice. It is simple, it works well, and it uses a very elegant way
of tracking the time.
I can think about implementing my own version later, but this will
handily suffice for now.
Polybar script will now limit the pomo timer to a single 'running'
instance containing the notification function, by putting its running
instance PID in a lockfile and killing it before restarting or changing
the timer.
Added running and paused tomato icons; as well as break coffee icon.
Removed display of seconds, unless the last minute of a timer is
running.
