* Removes outdated precommit scripts
* Updates eslint, prettier, stylelint and their configurations: turns on plugins that were installed but off
* Fixes stylelint errors
* Applies prettier to css files
* Fixes new eslint errors
* Updates lint script to include both stylelint and eslint
- When you try to commit, Pre-commit will run checks for all three, if
installed, _only_ on staged files, and prevent committing if the linters are
unhappy.
- Several eslint rules that generate a lot of errors are disabled for now.
That's to allow a more gradual transition, so you won't change 1 line and be
told to fix 100 other lines (but maybe like 20 because there are still a lot
of rules enabled).
- Prettier is set to require pragma. That's also to allow a more gradual
transition. As each file is tidied up, run Prettier on it, and it'll add a
special comment that tells it that it's now responsible for keeping that one
tidy.
