Add snap move

[bugeaud]

Once the piping items are snaped (see #6 ) we could add snap move that uses axis of liberty to enable you to move one item but keeping the other piping items snapped altogether.

In a way, this would work as the sketcher constraints : when moving, the solver must find a way to fit by changing the axis parameter (rotation or pipe size) so that it follows your move. If the move is not possible it should either block you.

This would be very usefull to route pipe in a given constraint environement (walls, depth, etc).