restructured manifest and plugins loading; updated plugins

plugins/youtube_download/yt_dlp/extractor/lynda.py

@@ -1,3 +1,4 @@
+import itertools
 import re
 import urllib.parse
 
@@ -216,7 +217,7 @@ class LyndaIE(LyndaBaseIE):
     def _fix_subtitles(self, subs):
         srt = ''
         seq_counter = 0
-        for seq_current, seq_next in zip(subs, subs[1:]):
+        for seq_current, seq_next in itertools.pairwise(subs):
             m_current = re.match(self._TIMECODE_REGEX, seq_current['Timecode'])
             if m_current is None:
                 continue