Adds a href prop to the right arrow Button in ExplorerItem. Opening this
link manually (such as Open Link in New Tab) will now take the user to
the deeper page list. Before this commit this button erroneously had no
href and thus would only take them to the current page.
* Remove useless CSS declaration
* Remove commented out styles
* Merge duplicate declarations
* Remove even more commented out code
* Move footer mq to footer declaration
* Remove more useless code
* Stop vendor prefixing for IE below 11
* Remove useless vendor prefixing
* Merge identical declarations
* Fix 1px overflow in content wrapper
* Fix explorer scrolling when open on mobile
* Remove unused import
* Add Redux performance measurements to explorer menu
* Rewrite explorer reducer to avoid unnecessary operations
* Stop changing reducer state on every action regardless of type
* Remove redundant children.isFetching property in nodes reducer
* Remove redundant children.isLoaded property in nodes reducer
* Remove redundant children.isError property in nodes reducer
* Refactor nodes explorer reducer with sub-reducer
* Fix linting issue
* Remove unused class name
* Change default icon className from empty string to null
* Remove old TODO comment
* Hoist icons in ExplorerItem component for better performance
* Add comment
* Add tooling for performance measurement of React components
* Clean up explorer panel component definition
* Make performance measurements opt-in
* Improve alignment of page explorer menu on mobile
* Close explorer on touchend rather than touchstart
* Comment out performance measurement code
* Remove fade transition completely
* Update to the latest jest version
* Update react dependencies
* Migrate React.PropTypes to PropTypes package
* Add prop-types to the package.json
* Update transition-group import to its new package
* Update jest snapshots
* Exclude node_modules from webpack babel-loader
