Refactor molecular calibration
A refactoring of the molecular atmosphere calibration with the following goals:
- timeseries request: increase robustness and account for the way the date will be specified when it will be actually running for b-c data (probably the now or yesterday we use are not optimal, since we don't know when we will actually run cat-B calibration)
- group information about sites: timezone, coordinates whatever else needed
- check for unnecessary parameters: e.g. do we really gridstep?