Add InputGeneratorWidget and dialog to QtGui.

Split the QuantumInputDialog in the QuantumOutput extension into
two classes in QtGui:
* InputGeneratorWidget: The dynamic configuration GUI/editor
* InputGeneratorDialog: A thin wrapper around the widget.

Change-Id: I1978bb858c2c71dadf54fab11ec64d902e5639c1
Merge topic 'input-generator-widget' into master

4c9aa5bd Add InputGeneratorWidget and dialog to QtGui.