New cli base, fixed InfluxDB export
- Change cli base to click
- Add support for wetterdienst core API in cli and restapi
- Export: Use InfluxDBClient instead of DataFrameClient and improve connection handling with InfluxDB 1.x
- Export: Add support for InfluxDB 2.x
- Fix InfluxDB export by skipping empty fields
- Add show() method with basic information on the wetterdienst instance