Initial commit of a new Swing API.
This is the first rough version of a Swing API that will be the framework for supporting multi-threaded capabilities in Flying Saucer. Currently has support for background document and stylesheet downloading and parsing, and image resource loading. I'm hoping that this will turn into support for incremental document rendering.
This API also generalizes the 'user agent' idea so that we can provide plug-in support for alternative HTTP networking code, caching, cookie handling, etc.
Updates to support browser like behaviour in the Swing 2 classes.