Log Message:
mkvtoolnix: updated to 49.0.0

Version 49.0.0 "Sick Of Losing Soulmates" 2020-08-02

New features and enhancements

* mkvmerge: added support for copying the new track header elements
  `BlockAddIDName`, `BlockAddIDType`, `BlockAddIDValue` and
  `BlockAddIDExtraData` from Matroska files if they exist.
* mkvinfo: added support for the new track header elements
  `BlockAdditionMapping`, `BlockAddIDName`, BlockAddIDType`, `BlockAddIDValue`
  and `BlockAddIDExtraData`.
* MKVToolNix GUI: multiplexer: the list of recent directories can now be
  edited in the preferences → "Multiplexer" → "Destination file
  name".
* MKVToolNix GUI: preferences: the values in the various "predefined \ 
values"
  lists can now be re-ordered freely by dragging & dropping.

Bug fixes

* mkvmerge: Matroska reader: when reading tracks (e.g. a subtitle track) from
  Matroska files with their `default track` flag set to `yes`, and when
  overwriting those via the command line to `no`, `mkvmerge` would not promote
  additional tracks of the same type from other files (e.g. another subtitle
  track from an SRT file).
* mkvmerge: SRT reader: empty lines inside entries were doubled.
* mkvmerge: subtitles: when calculating the rounded duration of each entry the
  error from rounding the corresponding timestamp will be taken into
  account.
* mkvextract: SSA/ASS extraction: mkvextract is no longer inserting empty
  lines before the `Dialogue:` lines.
* mkvextract: USF subtitles: start & end timestamps were too high by a factor
  of 1.000.000.
* MKVToolNix: info tool: when saving to a text file the checkbox "Save as
  default for saving output to text files" did nothing.
* MKVToolNix: info tool: when saving to a text file in "all elements in a
  tree-like structure" mode, the GUI always stopped at the first cluster
  regardless of the setting of the "verbosity" option.
* MKVToolNix GUI: preferences: when tooltips were disabled the dialogs for
  adding new entries to the various "predefined values" lists were missing
  their texts.
* Windows installer: the images are shown again.
* configure: fixed detection of QtDBus.

Build system changes

* libMatroska v1.6.1 is now required. The bundled version has been updated to
  that version.