First solution for issue #730. I've added two new pure virtual functions to AMCurrentAmplifier that return the min/max values for the given units. The refreshValues() methods in AMCurrentAmplifierSingleView and AMCurrentAmplifierCompositeView use these methods (implemented in CLSKeithley428 and CLSSR570) to display only valid values. Untested, as of yet.
Accidentally made reference to amplifier_ in AMCurrentAmplifierCompositeView, now changed to (correct) amplifier1_.
Added specific condition for (amplifierMode_ == Gain) in CLSKeithley428::maximum/minimumValueForUnits(QString).
Found bug where the largest value is excluded from the displayed amplifier value list in AMCurrentAmplifierSingleView::refreshValues(). Should be fixed now.
Added virtual destructor to BioXASSidePersistentView class.
Found a better way to write the max/min conditions for AMCurrentAmplifierSingle/CompositeView::refreshValues().
Fixed merge conflicts, and changed how custom context menus are handled by AMCurrentAmplifierView/SingleView/CompositeView.