add pre-commit config - Githubissues

Here we add a pre-commit config, so that styling, linting, spell-checking etc can all be performed locally on each commit.

TODO:

[x] exclude testdata/ and presentations/ from styling
[x] exclude docs/ from end-of-file-fixer (since autogenerated)
[x] ignore dependencies in presentations
[x] run linting in user environment, not isolated environment (to avoid object-usage lints)

russHyde / dupree