Suggestion/Bug: Using custom files as a source

[ethangarsia517]

If a user wanted to build upon a modpack's current music list (such as Hewdraw Remix), using it's own files as resources won't load/export the base's current playlist. It seems to default to vanilla's and they need to be redone from scratch.

The ability to use the Source playlist and ordering would help users build upon music packs that already exist.