* Stylelint: Ignore only top-level directories
The `.stylelintignore` entries lacked leading slashes, so most of the
UI code was ignored (because it fell under the `ui/app` directory, and
`app/` was ignored.
The leading slashes ensure only the intended top-level directories are
ignored.
* Simplify stylelint rules
We use the `stylelint-config-standard` rule-set, so most commonly-used
stylelint rules are inherited from that.
Some of the removed rules were redundant, some of them were more strict
than the rules in `standard` and we hadn't been following them in
practice, and some were obsolete.
* Convert stylelint config to JavaScript
JavaScript is a bit easier than JSON to work with, as it allows
comments.
This was also done to make it easier to merge in the `stylelint-config-
standard`, which is also in JavaScript.
* Inline `stylelint-config-standard`
I intend to go through each of these rules one-by-one, which is easier
with all of these rules inlined. Selectively overriding/disabling them
would have been messy.
* Comment out rules that aren't current working
These rules have been temporarily disabled. They will be re-renabled
one-by-one as they are fixed. This was done to make it easier to split
these changes among separate PRs, as many of the rules require
extensive functional changes.
* Add `stylelint` to `lint` script
`stylelint` is now run as part of the `lint` script. There is also a
separate `lint:styles` script for running just `stylelint`.
