Log Message:
mkvtoolnix: updated to 60.0.0

Version 60.0.0 "Are We Copies?" 2021-07-31

New features and enhancements

* all: IETF BCP 47/RFC 5646 language tags: added support for language families
  from ISO 639-5 that aren't part of 639-2.
* all: IETF BCP 47/RFC 5646 language tags: implemented support for Alpha 2
  country codes of the "user-defined" category: `AA`, `QM`–`QZ`, \ 
`XA`–`XZ` and
  `ZZ`.
* all: IETF BCP 47/RFC 5646 language tags: updated the various lists of valid
  subtags from the official specs.
* MKVToolNix GUI: multiplexer: pressing the keyboard shortcut for the track's
  "Language" label (Alt+L for English) will now open the language dialog.
* MKVToolNix GUI: multiplexer: added an option in the preferences for turning
  off the colored boxes indicating which file each track belongs to.

Bug fixes

* all: IETF BCP 47/RFC 5646 language tags: fixed validating extended language
  & variant subtags against their allowed prefixes (e.g. a valid tag with a
  country code as in `de-CH-1996` is recognized as valid while two generally
  known variants that aren't allowed together as in `de-1901-1996` is
  recognized as invalid).
* all: IETF BCP 47/RFC 5646 language tags: when looking up a language for a
  two- or three-letter code, the programs will no longer compare that code
  with language names as that was unintended, ambiguous (e.g. the code "Ga"
  could be interpreted as the 639-2 alpha-2 code for "Irish" or as the \ 
name of
  the language called "Ga") and only worked with languages whose name \ 
was at
  most three letters long.
* mkvmerge: HEVC/H.265: appending Matroska files with HEVC tracks might lead
  to the loss of the first couple of frames from each of the second and all
  following files.
* mkvmerge, mkvextract: HEVC/H.265 parser: fixed the programs aborting when
  parsing VPS or SPS NALUs with invalid content due to unhandled
  exceptions.
* MKVToolNix GUI: multiplexer: when the option "use legacy MIME types for font
  attachments" is enabled, the GUI will now use `application/x-truetype-font`
  for font collection files.
* MKVToolNix GUI: multiplexer: fixed escaping the `mkvmerge` argument in the
  "Show command-line options" dialog for the "Windows \ 
(cmd.exe)" mode.
* MKVToolNix GUI: multiplexer: when adding multiple files at once, the GUI
  will sort file names with numbers the way a human would expect it to. For
  example, `1.mp4`, `9.aac`, `10.srt`, `11.srt` are now sorted exactly that
  order instead of `1.mp4`, `10.srt`, `11.srt`, `9.aac`.
* MKVToolNix GUI: header editor: the header editor will now honor the "use
  legacy MIME types when adding font attachments" setting when adding new
  attachments.