- improve selection mode to create only one action for each clic
- fix problem on delete of some stiches

- add the interfaceDisplay class that will drive all the user interface and the display->controller interactions

- add instructions class
- add hoop, pulse/mm and zero point in document

- draw controls only for the selected curves and stitchs

- fix a bug in birailstitch class (initialisation of len and maxlen variable was not set)
- add the display of a point at 0,0

second move to a MVC design