++ Automatic offset for Dof::getType() of different FunctionSpace
          ## Need to be improved --> will add a lot of 'jumps' in DofManager

** Correction in SystemAbstract::assemble
     ++ Switching test function and field

** Lagrange Multipliers Formulations (Field tested by Lagrange and vice-versa)
     ++ Added a simulation to test that
          ## Same as FreeSpace but with constraint imposed by Lagrange

     ++ It works :-) !!