Convert mkv files to mp4

Current version

Revision: 1

mkvtomp4 requires the following formulae to be installed:
gpac 0.7.1 Multimedia framework for research and academic purposes
ffmpeg 3.3.4 Play, record, convert, and stream audio and video
mkvtoolnix 15.0.0_2 Matroska media files manipulation tools

Formula history

Mike McQuaid Use hash rockets again. (#5177)
Mike McQuaid Use Ruby 1.9+ symbol hash keys in all formulae. (#4942)
Zhiming Wang mkvtomp4: revision for ffmpeg update
Nikolaus Wittenstein Add descriptions to all remaining homebrew packages
Mike McQuaid mkvtomp4: don't depend on :python.
Mike McQuaid mkvtomp4: fix PYTHONPATH handling.
Mike McQuaid mkvtomp4 1.3
Mike McQuaid mkvtomp4: cleanup python usage.
Alex K mkvtomp4 1.2