Implement run-time testing

[t0mpr1c3]

Here's a quick run down of outstanding issues from eyeballing the code. Please suggest omissions and corrections. I haven't really looked in depth yet.

• The API has been revised so that Test Mode can be set from the desktop. The desktop software commands to enter test mode have been implemented but there are no equivalent steps in the finite state machine (addressed in PR Created GUI, Classes, and machine states for run-time hardware test ayab-desktop#415) and it does not log the serial output the GUI does not open a serial monitor (addressed in PR Created GUI, Classes, and machine states for run-time hardware test ayab-desktop#415). The firmware has not been updated to recognize the commands.

• Hardware test mode compile flags and instructions v0.80 legacy code need to be removed and the main loop refactored and the code refactored to comply with the new API and desktop GUI. (Addressed in PR Run-time hardware tests and other changes #38)

The hardware tests assume 16 solenoids. The tests need to be tried out on the KH270 which has 12 solenoids instead of 16.

There seems to be some code redundancy e.g. beep function.

• I couldn't find where the tests are documented. (Documentation issue raised Document run-time hardware testing ayab-manual#15)

[t0mpr1c3]

• The API needs to be changed so that the signal to start test mode includes information about machine type. Currently there is no way for the firmware to know what machine is in use during test mode. (Desktop changes implemented in PR Created GUI, Classes, and machine states for run-time hardware test ayab-desktop#415.)

[t0mpr1c3]

The API needs to be changed in the desktop software in accordance with the changes made in the firmware. When that is done, it will be ready for testing.