fix bug with substring search
avoid emitting key/value when not snowing
fix string comparison + improve key emission

- use s.indexOf("substring") != -1 to know if "substring" happens in s.
(s.contains is not meant for that)
- fix bug that causes no key/val to be emited if there was non-snow
precipitation, even if there was snow-depth data
fix bug with snow cumulation from snow depth