Grünlandtemperatursumme (GTS), a kind of Growing Degree Days

[Karen K]

Two of the weather networks I upload data to *) requested to send the "Grünlandtemperatursumme" (GTS), a kind of growing degree days, that is used in Europe, at least in Germany.

As the value was not provided by WeeWX standard, I tried to write an XType extension for that. And now, there is a first result. You find it there:

https://github.com/roe-dl/weewx-GTS

*) Wetternetz Sachsen and Regionalwetter Sachsen-Anhalt to be exact

[Karen K]

The extension provides the following observation types to use in skins and diagrams:

• GTS: the value of "Grünlandtemperatursumme" itself (example tag: $current.GTS)
• GTSdate: the date when the GTS value exceeds 200, which is considered the beginning of real spring (example tag: $day.GTSdate.last)
• utcoffsetLMT: offfset of the local mean time (Ortszeit) at the station's location
• LMTtime: a string showing the local mean time (Ortszeit) at the station's location (can only be used with ".raw", example tag: $current.LMTtime.raw)

[Karen K]

Umlaut seams not possible in install.py. Replaced by ASCII characters. See issue #1.