M20 Weather Support

[LukePrior]

Radiosonde auto rx now supports temperature and humidity decoding for M20 sondes along with pressure decoding if the sonde records that info. I know that M20 are one of the most common sondes decoded with this program so could be a useful addition.

Here are the changes in auto rx to add it: https://github.com/projecthorus/radiosonde_auto_rx/commit/6395cc430d8e0c996510fdaaf4e6a5ac1d438aa1

rs1729 temp: https://github.com/rs1729/RS/commit/b15ca44a4aa7b46e3bea3b3ccfb6e2c05c87b405 rs1729 humidity + pressure: https://github.com/rs1729/RS/commit/633615a8e586962d5bc627cf3fd73cb25e360316