* osm2bbd-postprocess: new target icao_metar
* bbbike: use icao_metar instead of icao, if it's there
* bbbike.cgi: add cacheprefix to wettermeldung file (if defined)

  This way there's no clash between bbbike.cgi invocations using
  different data directories.
* bbbike-osm.cgi.config: use icao_metar.pl for fetching weather data
  (if icao or icao_metar files are available)
* Strassen::CoreHeavy: in-code documentation that sort_records_by_cat
  is a static method
* new Strassen method sort_by_anything, together with a new test
  script strassen-sort.t
* data update