Enable option to always use files' paths with play

When using `play` with the `-a` option, the m3u has album's paths (folders) and some players can't open folders in a playlist. This PR adds a possibility to always use the paths of the albums' files instead of the album path.

I'm not sure if there are use cases for strictly using the albums folder paths, so I added a new config option, but IMO this could be a default option, and that's why I'm opening a PR instead of committing directly.