* Sensors: refactor configuration

- move sensor implementaion to the .ino,
  remove dependency undef / define from sensor files
- update test/build/sensor.h from SENSOR_SUPPORT
- allow to change sensor config variables externally
- `#include <...>` for global headers and libraries,
  fix relative path for math library

* add missing sns <-> i2c dependency

* ledrelay should return relay_none as default

* rollback to original test header

* include debug header when requested (relative)

* enable multiple Digital, Events & PulseMeter

* delete SPI dependency

* back to only one PulseMeter

* deprecared pins

- cache ms<->clockcycles conversions
- move callback invocation outside of ISR handler
- remember last event value