Core
* [extractor/common] Improve thumbnail extraction for HTML5 entries
* Generalize XML manifest processing code and improve XSPF parsing
+ [extractor/common] Add _download_xml_handle
+ [extractor/common] Add support for relative URIs in _parse_xspf (15794)
Extractors
+ [7plus] Extract series metadata (15862, 15906)
* [9now] Bypass geo restriction (15920)
* [cbs] Skip unavailable assets (13490, 13506, 15776)
+ [canalc2] Add support for HTML5 videos (15916, 15919)
+ [ceskatelevize] Add support for iframe embeds (15918)
+ [prosiebensat1] Add support for galileo.tv (15894)
+ [generic] Add support for xfileshare embeds (15879)
* [bilibili] Switch to v2 playurl API
* [bilibili] Fix and improve extraction (15048, 15430, 15622, 15863)
* [heise] Improve extraction (15496, 15784, 15026)
* [instagram] Fix user videos extraction (15858)