Stratux Serial output for EFIS's that support GDL90 or Flarm NMEA over serial

Serial output works equally to what is described here: https://github.com/cyoung/stratux/wiki/Stratux-Serial-output-for-EFIS's-that-support-GDL90-over-serial.

As of Stratux EU 017, it is additionally possible to output Flarm-NMEA via Serialout. To achieve this, change the serial device name as described in above article, but the name has to be "Stratux Serialout NMEA".