dynare 4.4.2: New formula

This formula was originally submitted to Homebrew as https://github.com/Homebrew/homebrew/pull/26815, and I was told to resubmit it here.

Though I work for Dynare, I hope you accept my submission for a new dynare formula to Homebrew. We hope to move Mac+Octave users to Homebrew, while giving Mac+Matlab the option to use Homebrew as well. We currently maintain the Dynare Debian package as well and will have someone to maintain this one as well (namely myself).

This formula does not run ```make check``` for two reasons. First, it takes upward of 5 hours to run our test suite. Second, I could not figure out how to patch the file that is currently patched (```dynare_config.m```) after running ```make check```. This file sets the appropriate paths in Matlab/Octave. Hence, when running ```make check``` before ```make install```, the way it's distributed with the source code is correct. However, to set paths correctly once it has been installed, it needs the patch that's applied in the formula. If you absolutely want to have our test suite run by default, please tell me how I can patch this file after running ```make check``` but before installing files.

Also, just to note, getting ```make install``` to work is on our todo list (https://github.com/DynareTeam/dynare/issues/576).