m300977: Added example_notbooks.rst to list notebooks in a reasonable order for documentation. Linking the notebooks into the documentation does not work so far.

Added notebooks/pyicon_view_Apollo.ipynb to demonstrate how to visualize R2B11 data with pyicon.view.

pyicon/view/pyicon_view_xr.py: Try to identify grid first by uuidOfHGrid, allow for specifying coordinates to enable plotting vertex variables, allow for plev (pressure levels) dimension.

Updates to calculate_xr and addition of tests

See merge request !11

pyicon/pyicon_tb.py: Added function rename_dimension_names to allow for unique dimension nams in data and grid file.

pyicon/pyicon_tb.py: Moved rename_dimension_names to pyicon_tb.py. This however needs to be optimized.

pyicon/pyicon_calc_xr.py: Fixed typo and removed value error if dimensions of vector does not contain same dims as dz (e.g. to allow also time dim) in xr_edges2cell.