The times we had

Adds a config flag for a new crawling mode.
This mode was specifically made for Radio FM4 because they recently had a website relaunch, where they removed the original trackservice webpage and replaced it with a web player. This player uses an API which luckily exposes track information.
My implementation targets only this API at the moment. If there are any other radio stations with a similar API, please open an issue so I can look into it, whether I can generalize this mode.