Magnatune Plugin

I wrote this plugin for [Magnatune](http://magnatune.com/). I'm not sure if I did everything as expected. E.g. I return the cover image in all available resolutions (marking those < 300x300 as thumbnails), I have to do redundant things between `getMeta` and `getLink` (it would be nice if `getMeta` would be executed before `getLink`) and `html_for_readability` contains the headline (should it? shouldn't it?).

Further I have to note that `embed.magnatune.com` does not set the correct content type of the swf file and so it only works when embedded using an `object` or `embed` tag, but not using an `iframe` tag. I wrote to John Buckman (the main guy behind Magnatune) about this yesterday but haven't received a reply yet. I hope he'll fix it soon. Maybe this shouldn't be merged before it is fixed? Or is there another (secure) way to embed a flash plugin with this tool?