VisVis with PyQt5

[JarrettR]

This doesn't run.

There are three causes:

1. ControlVisVis loading the default conf and then immediately checking it (default is set to PyQt4)
   https://github.com/UmSenhorQualquer/pyforms/blob/master/pyforms/gui/Controls/ControlVisVis.py#L22
   I don't know offhand how to elegantly solve this.

2. Base object QtGUI being referenced instead of the child
   https://github.com/UmSenhorQualquer/pyforms/blob/master/pyforms/gui/Controls/ControlVisVis.py#L31
   Solved by simply removing the QtGui. in front of QtGui.QWidget() and other instances

3. Passing VisVis hardcoded Qt4 string
   https://github.com/UmSenhorQualquer/pyforms/blob/master/pyforms/gui/Controls/ControlVisVis.py#L40
   Also easily solved by adding the if conf.PYFORMS_USE_QT5: conditional to self._app = vv.use('pyqt4')

[abr123]

I totally agree with @JarrettR . No.2 and 3 changes are small, but can help a lot.