Dynamically load output format options for the GUI

[KevinMcGee]

Instead of having the output formats hard coded into the GUI we should use the map that defines the formats and dynamically add the output options to the format selector. We'd likely want to set the key as the shown text and the value as the bit passed to the library. We should look at the QT Model hierarchy to see how to do that (http://doc.qt.io/qt-5/model-view-programming.html)