* Split no-unused-vars ESLint config to multiple lines

* Exempt variables prefixed with underscore from no-unused-vars rule

This is useful when e.g. using object spread operator to remove only a
certain field from the object.

For example, this can be used to ignore a property from React
component's `this.props`:

    render() {
        const { someAttribute: _unused, ...rest } = this.props;
        return <pre>{ JSON.stringify(rest) }</pre>;
    }

tagging dev-only code (@remove-on-publish-begin/end) and pre-eject-only code (@remove-on-eject-begin/end) #257 (#257)

This rule is considered dangerous in certain situations. This is especially true for Immutable.js users. See the discussion at issue #465 for more information about this.

* add off font format to loaders

* add otf format support

This is the one people are converging on, and flow-vars may get deprecated.

Fixes #260

* Use keyword `warn` in eslint config

We can use the keyword `warn` for rule configuration instead of a number.

* Fix comment which where WARNING was replaced

* Remove extra apostrophe

This project is a really good use case to apply some accessibility
rules to the lint config. For beginners getting started with React, we
can also teach/enforce basic accessibility rules in the web at author
time.

For now, I’ve just applied to the rules that are listed in
`eslint-config-airbnb` because these are most real-world tested, and we
can continue to add.

Happy to help if there are any questions/issues/concerns about the
plugin!

Ref #156

Not sure if we can simply delete the line and that'll disable it, so I
went with setting it to 0. Let me know!

* Make errors and warnings nicer

* Fix license stripping to not be eager

* Minor tweaks

* Use a custom eslint rule list

* Sort rules

* Relax some rules