Changes 4.6.0:
* build system: Fixed building the Qt version of mkvinfo's GUI (again).
* mmg: bug fix: If the header editor finds 'language' elements with ISO-639-1
  codes (e.g. "fra" instead of "fre" for "French") then it will map the code to
  the corresponding ISO-639-2 code
* mmg: bug fix: Fixed one of the issues causing mmg to report that it is
  configured to use an unsupported version of mkvmerge when the reported
  version was actually empty.
* mkvmerge: enhancement: HD-DVD subtitles are recognized as being an
  unsupported file format. This makes the error message presented to the user
  a bit clearer.
* build: Boost 1.36.0 or newer is required (up from 1.34.0). Also fixed
  building with v3 of Boost's filesystem library, e.g. with Boost 1.46.0
  Beta 1 or newer.
* mkvpropedit: new feature: Added support for adding, replacing and removing
  tags.
* all: Added a translation for the programs into Turkish by ßouЯock.
* build system: Fixed compilation if configure choses the internal versions of
  libebml and libmatroska while older versions are still installed in a
  location named with "-I..." or "-L..." in CFLAGS/CXXFLAGS/LDFLAGS or with
  configure's "--with-extra-includes" and "--with-extra-libs" options.

(adam)