Try to better keep the settings if we can when using the `IRac` class interface, if supplied a previous state. This better handles the short commands that don't have most of the settings in them.

Add unit tests to ensure it works as expected.

For #1780

* If we only have info from a _real_ short (command only) message, don't report other settings.

This makes text for single messages more accurate.
If the Class's state has been modified synthetically, report all the settings.

For #1780