CopyTagsToComments doesn't copy "covr" picture from quicktime/mp4/m4a

[ben-xo]

the quicktime atom for cover art is "covr", but I had to dig deeper to extract images - CopyTagsToComments works just fine for MP3 embedded artwork, however.

See ben-xo/dir2cast@5bf3616 for how I worked around the issue in my app (recursive search for 'covr' atom)

[JamesHeinrich]

getID3 by convention is supposed to copy attached images to the [][comments][picture] key, and then getid3:HandleAllTags will move (to save memory, avoid reduplicating large data) the pictures from the tag-specific comment section to the global [comments] section:
https://github.com/JamesHeinrich/getID3/blob/master/getid3/getid3.php#L1454-L1456
https://github.com/JamesHeinrich/getID3/blob/master/getid3/getid3.php#L1482-L1524

module.audio-video.quicktime wasn't doing that for covr atoms, it does now: c37956c