Description

Big PR (one of the last for this iteration!):

[ ] Adds documentation to GUI app,
[ ] changes the MoisturePidAnalyser to use a signal-based control of the pumps (using unix signals),
[ ] move lighting subsystem to use HW PWM (channel 0)
[ ] and Fans to use HW PWM (channel 1). This uses the linux driver for that PWM and works 1000 times better than software pwm.
[ ] Add new light intensity sensor profile and add to the analyser
[ ] Add PID value caching
[ ] Add colorful and modifiable logging
[ ] Add a safety wrapper with exceptions for the new light sensor, when it disconnects from i2c (to gracefully exit the app)

Issues

Closes #73 Closes #71 Closes #56 Closes #54 Closes #47 Works towards #36