Change windows management

Use 7 QDialog, avoid mainwindow
Add User management
Change a bunch of things

New structure for the user interface :
* Remove MainWindow
* Use Dialog windows
* main() controls every dialog and user data.
* Add a file for each dialog

New dependency: QCustomPlot in tools directory for ploting user progress

Add User management
* User list
* User data
* Load and save

Add Exercice management:
* UI
* Exercice generation

Add Calibration dialog:
* No actual feature yet

Fix: Wrong motion/command analysis, a wrong movement can corrupt the
whole sequence