The Honeywell HPM Series Particulate Matter Sensor is a
laser-based sensor which detects and counts particles using
light scattering.
This commit adds:
* The HPMA115S0 library by Felix Galindo
* selectable GPIOs for Tx and Rx (SoftwareSerial only)
* xsns_55_hpma.ino for Tasmota sensor implementation
Signed-off-by: David Hunt <dave@davidhunt.ie>