plugins.bbciplayer: add dash support
plugins.bbciplayer: add dash support

beardypig/streamlink,gravyboat/streamlink,chhe/streamlink,javiercantero/streamlink,wlerin/streamlink,streamlink/streamlink,melmorabity/streamlink,back-to/streamlink,chhe/streamlink,bastimeyer/streamlink,javiercantero/streamlink,wlerin/streamlink,bastimeyer/streamlink,beardypig/streamlink,back-to/streamlink,melmorabity/streamlink,streamlink/streamlink,gravyboat/streamlink