Log Message:
mkvtoolnix: updated to 40.0.0

Version 40.0.0 "Old Town Road + Pony":

New features and enhancements
* mkvmerge: MP4 reader: added support for BMP covert art images.
* MKVToolNix GUI: multiplexer: added an option to disable deriving the
  destination file name from the file title.
* MKVToolNix GUI: multiplexer: the content of the "stereoscopy" combo \ 
box has
  been simplified making the box's minimum width much smaller, allowing the
  user to resize the GUI's whole window to a much smaller width.
* MKVToolNix GUI: multiplexer: whenever the user changes the "aspect \ 
ratio" or
  "display dimensions" controls, the corresponding radio button will be
  activated automatically.
* MKVToolNix GUI: Windows: added a setting in the preferences to disable the
  GUI's dark color mode even if Windows's app color mode is set to
  dark.
* MKVToolNix GUI: Windows: replaced the dark mode introduced in v39 with
  another dark mode that's less wasteful with space between widgets.

Bug fixes
* mkvmerge: MP4 reader: mkvmerge was reading eight bytes too many for cover
  art images. This could cause file identification to fail when the cover art
  was located at the end of the MP4 file. Even if it succeeded, this meant too
  much data present in the attachment.
* mkvmerge: MP4 reader: covert art images with unknown image types will be
  skipped instead of treated as JPEG images.

Build system changes
* Qt 5.9.0 or newer is now required for building MKVToolNix GUI.