`moose-gui` does not launch on MacOSX

[dilawar]

This ticket is here to track the status of moose-gui on MacOSX.

Run launch GUI, one needs to install PyQt using brew.

  $ brew install pyqt

Currently, pyqt-5.8.2 is available on homebrew. The moose-gui does not launch with this version.

$ python mgui.py 
Traceback (most recent call last):
  File "mgui.py", line 57, in <module>
    from PyQt4 import QtGui, QtCore, Qt
ImportError: cannot import name QtGui

It is unlikely that old version of pyqt are tapped somewhere on homebrew (though I am not sure about this). See the their transition status to (https://github.com/Homebrew/homebrew-science/issues/4595). Until moose-gui run with pyqt5, gui will not be available on MacOSX via homebrew.