Fix minor typos

[pkestene]

Add pre-commit hooks config and fix reported typos

This PR adds configuration files for using pre-commit, e.g.

• remove trailing white space,
• end of file fixer,
• spell checker (typos).

It can be run in command line terminal with pre-commit run --all-files (pre-commit is available either as a system package in Debian/Ubuntu or from a python package manager) . It could in principle be placed in a CI script, but it sometimes detects false positives (e.g. abbreviated variable names), so it is better to have a human eyes to cross-check.
False positives can be listed in _typos.toml so that they are ignored by the spell checker.

[tim-griesbach]

Thanks for the PR! This looks good to me! The whitespace checking is a useful addition. I think it makes sense to unify the spellchecking since we have the script scspell calling codespell as well using doc/codespell_ignore.txt. One option would be to use codespell in the file .pre-commit-config.yaml instead of typos.
What do you think @cburstedde?

[pkestene]

Hi @tim-griesbach
I think both tools are useful and can be kept. typos was able to spot misspellings at some locations that had not been identified before. These are different tools with the same purpose; there is a comparative table there : https://github.com/crate-ci/typos/blob/master/docs/comparison.md

[cburstedde]

Thanks for the contribution and discussion, I think we can keep various tools around.
Wondering, what's a good place in the documentation to point at the current set of three: pre-commit, typos, codespell.
Would it make sense to add a paragraph that it is recommended to run some or all of them before submitting code?

[cburstedde]

Comparing with the analogous PR in p4est, would it be possible to shorten the exclude list in this PR?