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- fixed issue where creating ``Fieldset`` slices of more than 10 fields or so did not work
- allow the creation of a ``Fieldset`` object, either empty ``Fieldsest()`` or with a path to GRIB ``Fieldset('/path/to/grib')``
- added ``append()`` method to a ``Fieldset`` to append ``Fieldset``s to ``Fieldset``s
- the ``dataset_to_fieldset`` function that converts an xarray dataset to a Metview ``Fieldset`` now accepts the ``no_warn=True`` argument to suppress warnings while the xarray GRIB writer is pre-beta
- ignore errors on exit from a data examiner
- added more example Jupyter notebooks