another optimisation to curl operator to reduce number of tasks in compute_curl and prevent memory overload

Makes new daskicon class for more efficient processing by pointing directly to the coeff files on disk

Optimises xr pyicon calculations for Dask mp and adds a few other edge and cell conversions for computing curl etc

Various plotting things like robustsym clim. Adds edge, vertex, cell conversions for curl calculation for xr.

Fixes for EERIE ICON data format when plotting certain sections. Discrepancy between clat and lat. Adds input for selecting resolution when interpolating to rectgrid.

quickplots : try if variable ssh is available, if not try zos

See merge request !29

pyicon_tb.py: Allow for antialiasing and masking in interp_to_rectgrid_xr. Add more grids. Added hp_add_dims.

Part 1 of plotting fixes

See merge request m300602/pyicon!28

Fixes problem with crop-tgrid

See merge request m300602/pyicon!27

updated gitlab-ci to install requirements before building the documentation....

See merge request m300602/pyicon!26

updated gitlab-ci to install requirements before building the documentation. This enables autodoc to find the docstrings in the python files.