Support Spotify Premium Audiobooks Download

[saragrab]

Currently when trying to download an audiobook it just shows
"there is nothing to do"
It seems that format is different for audiobooks and currently are not supported.

[DraftKinner]

Yes, audiobooks are currently not supported. Not sure if librespot is able to stream them, will have to see to know if support is viable.

[saragrab]

Thanks!

[gjoseph]

@DraftKinner it appears librespot supports it, though I'm not sure I understand the details here: librespot-org/librespot#1588
Is this the version/fork of librespot you're using? If so I might try to give a crack at patching zotify for it -- if/when time permits