MKVToolNix (64-bit)

What's new in this version:

New features and enhancements:
- mkvextract: WAV extractor: mkvextract will now write W64 files instead of WAV files if the file name extension is `.w64` or if the final file size is bigger than 4 GB, the file size limit for WAV files. Implements #2458
- MKVToolNix GUI: multiplexer: a new button was added next to the "destination file" controls. Clicking it shows a menu with the ten most recently used output directories. Selecting one of them will change the destination file to the selected directory keeping the file name
- MKVToolNix GUI: multiplexer (preferences): the ten most recently used values for the "relative output directory" and "fixed output directory" settings are now saved. The corresponding settings have been changed into combo boxes allowing quick access to those recent values
- MKVToolNix GUI: multiplexer (preferences): the predefined split sizes and durations can now be customized in the preferences
- MKVToolNix GUI: chapter editor: added an option in the "Chapter editor" menu for appending chapters from an existing file to the currently open editor tab
- MKVToolNix GUI: chapter editor: added an action in the context menu for copying the selected entry and all of its children to another open editor tab

Bug fixes:
- mkvmerge: all files opened for writing will now be flushed once before they're closed. This ensures the operating system actually writes all cached data to disk preventing data loss in certain situations such as power outages or buggy drivers in combination with suspending the computer
- mkvmerge: AAC: under certain conditions 8 channel audio files were taken for 7 channel ones
MKVToolNix GUI: multiplexer: removing a file added as an "additional part" will no longer cause a crash
- source code: fixed compilation with Boost 1.69.0 after API-breaking change to the `boost::tribool` class