1. Add ale.setup and ale.setup.buffer for pure Lua configuration.
2. Update many global settings to use Booleans instead of numbers to
make types easiert to work with in Lua.
3. Radically reformat documentation and fix errors to make
documentation more usable for Neovim users.
* Add support for AVRA linting
* Add tests for AVRA linting and improve code
* Fix test
* Fix warning detection
* Fix test
* Fix test
* Add AVRA as a supported language in docs