The rotate action shortcut was 'space' before this commit and so the
keyPressEvent with space key was never propagated because always grabbed
by the rotate action.
Now the shortcut for the rotate action is ctrl + space.
Note that even if rotate exist in element editor, this doesn't work well
because the rotation is not well managed by the save/load from elmt
file.
* Some types of elements need to specialize the setRotation method in order to behave correctly :
- PartTerminal needs to call setOrientation
- PartLine, PartRectangle and PartPolygon need a different rotation center.
