New implementation of the heart rate sensor data processing using a frequency based PPG algorithm.
The HRS3300 settings are fine-tuned for better signal to noise at 10Hz.
The measurement delay is now set to 100ms.
Enable and use the ambient light sensor.
FFT implementation based on ArduinoFFT (https://github.com/kosme/arduinoFFT, GPLv3.0).
Don't use relative imports like `../foo.h` as those depend on the
relative position of both files. Rather than that use imports relative
to the `src` directory, which explicitly is part of the include
directories.
