Code cleanup, small design changes and better file handling

I did some changes to the original fork from Yamanelow.
* Recursive file search and search bar. This was important for me, because I have all my music in subfolders. At the moment the search is only client side. Not very good for large music librarys.
* I renamed the playlists created by Yamanelow to Playlist 1-10
* The controll buttons aren't fixes any more. Otherwise they may hide parts of long playlists.
* Different files for css and js. Much cleaner!