1.6.0

• feat(danmaku): add retry
• feat(youtube): add_caption()
• feat(huya): rework parse_stream_info()
• feat(main): join all threads
• feat(main): custom datetime_format for Windows compatibility
• feat(main): update to python3.7 for asyncio.run()
• feat(ffmpeg): update ua
• feat(huya): remove DISABLED_CDN_TYPE
• feat(utils): add huya_danmaku.py
• feat(youtube): add insert_into_playlist