Out of @yan12125's concern that the presumption that JWPlayer data as
an array representing multiple formats rather than a playlist might be
specific to IQM2, move this code from jwplatform.py to iqm2.py.
JWPlatformBase now reverts to throwing a TypeError if it gets an
array.
Now IQM2 redefines the _extract_jwplayer_data() method as well, but it
continues to leverage JWPlatformBase for _parse_jwplayer_data(), which
is the bulk of the work.
02f4d4e44f