[dbtv] Add new extractor
Merge branch 'dbtv' of https://github.com/mrkolby/youtube-dl into mrkolby-dbtv

Conflicts:
	youtube_dl/extractor/__init__.py
[dbtv] Simplify, modernize, extract all formats
Merge branch 'mrkolby-dbtv'
Credit @mrkolby for dbtv.no (#3685)