Cycleball Radball timer

This code enables you to run a timer on a micro:bit that is suitable for Cycleball, also known as Radball. It enables you to select a timer for 7 minutes, or: 6,5,4,3,2,1,-,=,M,20,15,10,9,8. Whereby these are match minutes, - is 30 seconds, = is 30 seconds on repeat and M is 7min+break+7min.
These represent the minutes before a buzzer sounds. The display scrolls the numbers, as it counts down the minutes. Once running, the timer can be paused or reset. A case and clip make it robust, and a loudspeaker and battery pack give it sufficient volume. See user-instructions.txt for further details on how to operate the buttons.
Please see micro:bit instructions for how to upload a file (e.g. using Thonny and copying file named main.py across to the micro:bit while holding the button)