MKVToolNix 7.3.0

Update to [latest stable release](https://www.bunkus.org/blog/2014/10/mkvtoolnix-v7-3-0-released/), add option to build [experimental QT GUI](https://trac.bunkus.org/wiki/MkvToolNixGuiStatus), add libmagic as recommended dependency, upgrade flac dependency to recommended, downgrade gettext dependency to optional, remove unnecessary configure options locating ogg and vorbis, change format of ```drake install``` command.
    checking for moc-qt5... no
    checking for moc... /usr/local/bin/moc
    checking for the Qt version /usr/local/bin/moc uses... too old: 4.8.6
    ==> Formula
    Tap: path or URL
    Path: /Users/David/GitHub/homebrew/Library/Formula/mkvtoolnix.rb
    ==> Configuration
    HOMEBREW_VERSION: 0.9.5
    HEAD: ffa52f3fbb24c2331cb5e4c457667b116cf2a91c
    CPU: quad-core 64-bit sandybridge
    OS X: 10.10-x86_64
    Xcode: 6.1
    CLT: 6.1.0.0.1.1413057044
    X11: 2.7.7 => /opt/X11
    ==> ENV
    HOMEBREW_CC: clang
    HOMEBREW_CXX: clang++
    MAKEFLAGS: -j4
    CMAKE_PREFIX_PATH: /usr/local/opt/expat:/usr/local/opt/qt5:/usr/local
    CMAKE_INCLUDE_PATH: /usr/include/libxml2:/System/Library/Frameworks/OpenGL.framework/Versions/Current/Headers
    CMAKE_LIBRARY_PATH: /System/Library/Frameworks/OpenGL.framework/Versions/Current/Libraries
    CMAKE_FRAMEWORK_PATH: /usr/local/opt/qt5/Frameworks:/usr/local/opt/python/Frameworks
    PKG_CONFIG_PATH: /usr/local/opt/xz/lib/pkgconfig:/usr/local/opt/libogg/lib/pkgconfig:/usr/local/opt/libvorbis/lib/pkgconfig:/usr/local/opt/expat/lib/pkgconfig:/usr/local/opt/pcre/lib/pkgconfig:/usr/local/opt/flac/lib/pkgconfig:/usr/local/opt/d-bus/lib/pkgconfig:/usr/local/opt/qt5/lib/pkgconfig:/usr/local/opt/ruby/lib/pkgconfig
    PKG_CONFIG_LIBDIR: /usr/lib/pkgconfig:/usr/local/Library/ENV/pkgconfig/10.10
    HOMEBREW_BUILD_FROM_SOURCE: 1
    ACLOCAL_PATH: /usr/local/share/aclocal
    PATH: /usr/local/opt/python/bin:/usr/local/bin:/usr/local/Library/ENV/4.3:/usr/local/opt/xz/bin:/usr/local/opt/pkg-config/bin:/usr/local/opt/expat/bin:/usr/local/opt/pcre/bin:/usr/local/opt/flac/bin:/usr/local/opt/d-bus/bin:/usr/local/opt/qt5/bin:/usr/local/opt/ruby/bin:/usr/local/opt/python/bin:/usr/bin:/bin:/usr/sbin:/sbin
Otherwise, for me it's finding qt4's in ```/usr/local/bin```. Should that precede the others in the PATH, or do I have a misconfiguration somewhere? ```brew doctor``` doesn't have any complaints.