Make WebView Accept HyperlinkListeners

There is currently no nice way to attach a `HyperlinkListener` (or a similar interface) to JavaFX' `WebView`. The mechanism which would have to be used is clear though, see [here](http://stackoverflow.com/questions/17555937/hyperlinklistener-in-javafx-webengine) and [here](http://blogs.kiyut.com/tonny/2013/07/30/javafx-webview-addhyperlinklistener/), so an implementation should be easy.
