Add icon-vis exercise

[AnnikaLau]

• This exercise requires the icon-vis repo to be added to the environment, so it assumes that the icon-vis repo is in the same directory as the pyvis repo.

• If the users should be able to plot all example plots, the env/setup-conda-env.sh file in the icon-vis repo needs to be sourced, which works only on Daint or Tsa. However, we can also decide that they cannot work with all example plots in the repo.

Let me know what you think of the exercise and the point above

[chadhat]

@AnnikaLau @mathause are you done with the changes on this branch?

[mathause]

I can go over it later.

[AnnikaLau]

I'm currently waiting for feedback from my co-developer of icon-vis Victoria Cherkas. So we could actually wait and see what she thinks.

[AnnikaLau]

I also created some slides to explain what icon-vis/psyplot/iconarray is. You can also have a look at them if you like: https://polybox.ethz.ch/index.php/s/azk90Dwvkh40LDK

[AnnikaLau]

I made some more changes according to Victoria's feedback.

@chadhat can you update the environment including adding icon-vis? I would still need to try out the exercises on the environment.

Apart from that I'm happy if you have a look at the exercise (again) and for your review.

[AnnikaLau]

@chadhat: From my side, I resolved all review comments. Please let me know if you are happy with the final version. Then we could merge and test it on the pre-installed environment.