Merged requested to merge nemuii/podcasts:207-soundcloud-playlists into master
Only soundcloud user feeds were supported until now.
This adds playlist rss feed support and closes #207 (closed).
test if there is a user page that also contains a playlist id
maybe check for https://soundcloud.com/[a-z\\-]/sets/[a-z\\-]
add test case
cargo fmt, rebase