- add OE_controller::getSelectionBoundingBox function
- rename "select" function to "picking" in OE_interfaceDisplay (more clear name)
- change selection mode into an editionState in OE_interfaceDisplay
- add scale method to curves and stitchs
- add ScaleSelection state and implement the scale selection actions and UI widget
- clean and comment OE_interfaceDisplay
- add BoundingBox::getCenter method
- add OE_display::screenToDocument method

- store the len value of the birailStitch
- add the move function to staticStitch
- add getStitchStart and getStitchEnd method to OE_linkstitch
- fix a bug in OE_linkstitch::refresh method (it always put needRefresh to false)
- add double point motif to OE_linestitch
- add OE_actionDelStitch
- fix a bug in refreshDependency of most stitches and curves (does not refresh dependency of their own dependency)

- add actions for moves
- add - operator to vector_2d class

- add some actions to clear selections