Mock time series for tests

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As a first step, I can pull some data from a real station somewhere. Formating and importing can be done after #2 is completed.

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Variables:

• Date
• Temperature
• Humidity
• Precipitation
• Windspeed
• Wind direction
• Pressure
• Air quality

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Partially solved in 96f895b. What's missing is an import into the DB and smoothing by e.g. rolling window.