Ability to add additional directory sources

[micolous]

It'd be nice to be able to add additional directory sources. My ISP offers unmetered access to certain radio streams locally. They offer playlist files in a variety of formats, and it would be nice to be able to use one of them with your plugin to be able to automatically have their radio stream list updated automatically. Looking at the files, it would be probably be best to use the OPML format playlist file.