Nionswift-instrumentation

-------------------
- Fix issue with subscan handling during SI.
- Improve exception handling during camera initialization.
- Add support for time-based initial calibration style for scans.

-------------------
- Fix metadata handling in scan devices (was not copying it to the image).

-------------------
- Fix multi acquire data item calibration handling.

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

-------------------
- 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.

-------------------
- 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.