(ARCalibration): improve the widget layout in the calibration activity.
Description
The activity is poorly displayed on 16:9 screens most of space is empty and the video occupies a tiny fraction of the window (about 1/9th).
Proposal
- Put the calibration info widget and calibration result on a column on the left or right side of the app.
- Increase the scene's (video) size.
- Display detected chessboards in the same window.
- Make icons smaller?
- Add shortcuts.
See #251 (closed)