1st commit, new GUI
New GUI ok
Add KeyPressEvent function

NEW : ESC was unselecting the widgets if the mouse was interacting with a vtkInteractor. If not (while interacting with the options), ESC did not unselect them. By using keyPressEvent we can do it.
Center options enhanced

NEW : add reset_center to put back the meshes to their origin
NEW : display if the mesh is centered or at his original position
Merge pull request #1 from agirault/version2

Version2