Re #5896. Remove calls to deprecated method that does nothing.
Re #5896. Don't expose to python things that can be set via properties

For things that have been declared via Q_PROPERTY on the C++ side, we
can use setProperty to set them and keep the number of methods explicitly
exposed to python to a minimum.
Re #5896. Add live button to DGS Reduction GUI.

Includes adding infrastructure to do it more generally in these python
interfaces.
Re #5896. Use new-style PyQt signal-slot connection syntax.
Re #5896. A mechanism to change settings when live button is pressed.

Some settings are not applicable or need to have certain values for
live reduction. This allows other settings (even in different tabs)
to be set or disabled when the live button is pressed.
Re #5896. Fix certain settings in DGS gui when live button pressed.

This fixes the values of certain aspects and disables the gui elements
when the live button is depressed. Any changed settings are remembered
and reverted when the button is unchecked.
Re #5896. Spelling correction.
Re #5896. Ensure signal is emitted if state changed programatically.

Switch to a signal that is emitted whenever the state of the button
changes, not just when it is manually clicked.
This ensures that items are properly disabled if the live button starts
out checked. It appears to have no negative effect on the Step Scan GUI
(which is the other place listening to that signal).
Merge branch 'feature/5896_reduction_gui_live_again' into develop