Nionswift-instrumentation

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- Fix multi acquire data item calibration handling.

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- Change camera to use instrument controller (generalized stem controller).
- Add stubs for 2D control methods.

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- Add synchronized acquisition of sub areas and lines.
- Expand ability of custom devices to specify calibration and processing.
- Add multi-acquire panel for acquiring multiple summed sets of spectra with optional energy offsets.
- Support subscan rotation and subscan resolution.
- Improve handling of default stem_controller for camera, scan modules.
- Change shift output messages to match sign of change.

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- Change camera exposure time and scan pixel time to have two digits of precision.
- Add 'synchronized state' messages to instrument controller, invoked at start/end of synchronized acquisition.
- Limit scan device pixel time in the case of long camera exposure during synchronized acquisition.

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- Fix closing bug in state controller leading to errors when closing document window.

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- Change spectrum and 4d images to go into new data items each acquisition.