Fleshout some: Take single, better lockin manage

Work on take single has started which has necessitated going back and
fleshing out the other functions. All of this is untested with real
equipment, but the typechecking of QT makes me think it will likely work
ok.

multiple Lockins are now new instantiations of lockin7265 with a GPIB
address read once from the UI when instantiated.