PR #13: Don't block GUI when loading data and calculating correlation coefficient
PR #18: Fix a bug when browsing climate stations
PR #19: Improvements to the WeatherStationDownloader window.
PR #20: cache data once it is loaded from the working directory
PR #22: Fix fetch stationlist and add a station inventory file to ressources (fixed #21)
PR #24: Fix gapfill button layout
PR #25: Cache correlation coefficients