Work in progress: Rewrite to a simpler PHP backend.

The backend only delivers JSON and playlists, but will not generate
the HTML anymore.  Javascript will take care of that.

Anyway, almost nothing works at this stage.
Use jquery instead of document.getelementbyid calls.

Search/replace, so I've probably left something out.
Early implementation of jwPlayer 5.

Only works for single files, and look horrible.