Bug 1093219 - m3u parsing

Also, you're not loading anything, so I think you should just call this parse(). Also, I wonder if this would be more convenient as a factory method that takes a filename and the file content string and returns a Playlist.  That is, which is the nicer API, this:

```
var playlist = new Playlist(filename).load(fileContent)
```
Or:

```
var playlist = Playlist.load(fileName, fileContent)
```