MKVToolNix (64-bit)

What's new in this version:

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

Fixed:
- 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. Fixes #2888.
- 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