LagrangeSimplex does not implement partial() for dim=1

The case dim=1 and k > 1 is somehow missing in the implementation of partial() in LagrangeSimplexLocalBasis. Probably this was missed when moving the PkNd Implementation into the LagrangeSimplex implementation. I suggest to implement the missing case dim=1 and maybe also the dim=3 case, it should not be much more complicated than the dim=2 case.