title: Could not find Doxygen (missing: DOXYGEN_EXECUTABLE) in Mac OS X
body: <p>I want to install meta on my Mac OS X. I have OS X 10.9.3, and I received the following errors:</p>
  
  <pre><code>   DICU_ROOT=/usr/local/opt/icu4c
  -- Compiler supports C++1y (using it)
  -- Could NOT find Doxygen (missing:  DOXYGEN_EXECUTABLE) 
  -- Locating libc++...
  -- Located libc++, using it.
  --     Locating libc++'s abi...
  --     Found libc++abi, using it.
  -- Could NOT find Doxygen (missing:  DOXYGEN_EXECUTABLE) 
  -- Configuring done
  -- Generating done
  -- Build files have been written to: /Users/sara/meta/build
  MacBook-Air:build sara$ brew install DOXYGEN_EXECUTABLE
  Error: No available formula for doxygen_executable 
  Searching formulae...
  Searching taps...
  saras-MacBook-Air:build sara$ meta
  -bash: meta: command not found
  saras-MacBook-Air:build sara$ build
  -bash: build: command not found
  </code></pre>