Update shift widget
Merge MR !96 (merged) first!
This MR updates the Shift edition widget:
- Fix an issue with the display of Preview plot: 0f7c1b0f
- Replace Eta by scan names to avoid hard coded Eta, closes #7 (closed)
- Allows to display either the integrated intensity or any other measurement (what's available in normalizers in the intensity view), related to #55 (closed)
There is also some rework/clean-up of the code.
Is the data that can be visualized in the ShiftView enough?