Fix spelling mistakes

[EwoutH]

This commit fixes a bunch of spelling mistakes, found and fixed by codespell v2.2.1. All fixes are checked by hand to be actually a fix for an actually misspelled word.

Still in draft because I need to check a few special cases and the Jupyter Notebooks.

Once those are fixed or added to a ignore list/file, I plan to also add codespell to the pre-commit CI to catch future errors.

[review-notebook-app]

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See visual diffs & provide feedback on Jupyter Notebooks.

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[coveralls]

Coverage remained the same at 81.139% when pulling ecce695 on EwoutH:spelling-fix into 6652129 on quaquel:master.

[EwoutH]

@quaquel Quick update on this effort, and a few questions:

1. Codespell might have found a legitimate bug in ema_ipyparallel.py, where daemon is misspelled as deamon, can you take a look at that? See 2b3d387 for the diff.
2. Codespell found mistakes in the Sales_Agent_Market_Building_Dynamics.mdl test model. Do we want to fix spelling models in those? See 707ba35 for the diff.

Furthermore I looked into adding codespell to the pre-commit configuration. Unfortunately, it's still to too buggy for that, and mainly blocked by codespell-project/codespell#2138 (images in Jupyter Notebooks get sometimes corrupted). Which is a shame, because it would be really useful catching mistakes in PRs.

[quaquel]

1. The code prior to the fix is indeed wrong so the fix is welcome. It is however a bug with very low impact. It only affects the shutting down of the overall program. However, ipyparallel is typically used in conjunction with Jupyter so there everything is handled through the notebook.
2. I don't want to fix stuff in the underlying models. Changing the mdl requires changing the vpm file as well and that means I need access to a windows pc with vensim.

[EwoutH]

I threw out the spelling fixes in the Vensim models and the weird Juypter notebook image issue. I also resolved conflicts.

This PR is now ready for review. Please squash when merging.