Draft: WIP: i2psnark: js audio playlist

This is some js that adds buttons to play all the audio files in a directory without having to click on the m3u link to an external player. This is a proof of concept, no CSS updates are included to style the buttons or highlight the playing track. This uses the existing players, one for each track. An alternative is to replace all the per-track players with a single one that has all tracks in it.