UPDATE: pyQt4 based dialogs

qtqui.py is intended to end up being a pyqt4 replacement for the current wx based gui.py
functionality.

Implemented:

* file dialogs
* base Dlg class
* alert dialog types.

Missing:

* the DlgFromDict class (will add tomorrow).

qtgui.py can be run as a demo script and will display each implemented
dialog type.

**Only tested on Windows so far!**