Add section plot

[tillmrtz]

Creating new Pull request, since I accidentally created one only for my fork

[tillmrtz]

The section plot does takes several arguments, such as all variables that should be plotted, the vertical resolution in meters, start and end profiles to plot and also a possible dataframe containing the mld information: plot_section(ds, vars=['PSAL', 'TEMP', 'DENSITY'], v_res=1, start=None, end=None, mld_df = None). In addition to the x-axis representing the profile numbers, a time axis is plotted below.

[MOchiara]

Looks good to me! The segmentation errors you are getting is something I think Callum is working on

[callumrollo]

ok, so it took me almost a year (sorry!) but I did fix those segfaults in the tests.

Looks pretty good to me! I don't think we want the conda lock-file env.yml though? The addition of cmocean to the requirements files that you made should suffice

[tillmrtz]

Locally most tests ran okay, somehow a RunTime Error for the test_plots script now.

Also, the test_mission_summary script produces problems locally. Seems to be okay when trying to merge here!