"Download folder" in SoulseekQt and Nicotine+ asks the sharer for that
one folder (peer code 36) instead of the whole share, and a sharer that
never answers leaves the folder download hanging. The requested folder
now comes back as a FolderContentsResponse (code 37), which carries a
directory listing in the same form a browse does, so the two share one
codec. The browse and folder replies also share one reply helper.