Log Message:
libmatroska: updated to 1.6.2

Released v1.6.2.

* In release 1.6.1 the version number in CMakeLists.txt wasn't
updated, affecting the installed cmake and pkgconfig files. The
version number has been bumped to 1.6.2 in all relevant files now.

Released v1.6.1.

* "KaxBlockAddIDValue" class: this class is no longer marked as
"mandatory" in order to coincide with the latest specification.