r10935/sofa : customGUI: basic interaction works
r10935/sofa : customGUI: basic interaction works

Click and drag (without Shift) the white points to interact with the scene.
Todo: find how to use Shift with glut. It seems undetected, is is a bug in freeglut ?
Todo: make the interaction policy more flexible. Currently only the default interaction is possible.

Former-commit-id: fd369ecbe31c2b5ce31c65bf39608ab66f0f3a9b
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