Coala is basically dead -> no major commit in over 2 years. It's getting outdated python-wise (in fact, I had to uninstall some bears to run on CI). It's never been _that_ functional either way.
This diff proposes to replace it with just the regular old arclint. The main reason to not use arclint originally was that:
- you need to have the linter installed to work with arcanist
- doesn't have eslint
These are both true, but honestly whoever install arcanist can install eslint :P
This uses a script from https://secure.phabricator.com/D12198#209409 for eslint and custom python crapiness for licence year bear (need improvement).
**Pros**:
- arc lint only shows messages for affected lines by default, which means we can avoid the mess that we're in wrt to superfluous linting
- more integrated -> runs on "arc diff".