Add support for local songs

[pncnmnp]

There may be times when users have their songs stored locally. In these cases, they may not need to use youtube-dl to retrieve the songs again. It would be a good idea to add support for locally stored songs.

Ideally, this feature should allow for both the specific path name of the song and a directory name for retrieving a set of random songs. Perhaps an intelligent fetch could automatically detect artist names as well?

[pncnmnp]

I have a feeling that the schema is becoming overly complicated with features like these, and there needs to be some simplification for the music-* key.

[ology]

I have dreamed of this feature, but didn't know how to implement. :)

[pncnmnp]

Okay, the fact that you've dreamed of this as well has got me excited! 😃 There's a messy way and a clean way to do this. I'm familiar with the messy way, so I'll start there and work towards creating something maintainable.

[ology]

Sweet! (Context: I have like 11.8k music tracks on my external, and I would like to make radio shows for myself and friends with total control over the exact song chosen.)

[ology]

After I see your "messy way", maybe I'll get a clue and figure out how to make things smoother. :-)