CUDS: Lattice size, origin and base_vectors should be always in 3D

[itziakos]

This will allow defining lattices that are in the XY, YZ, XZ planes. Such lattices will be also easier to visualized next to full 3D lattice instances.

[kemattil]

There is now a SSB decision on this (teleconference on 17th April, see point 2.2 in meeting minutes at https://publicwiki-01.fraunhofer.de/SimPhoNy-Project/images/f/fd/Minutes_SSB_20150417.pdf).

That is, SimPhoNy deals only with 3D models. Hence, lattice attributes and method arguments should be in 3D (including node indexes).

[itziakos]

Thanks @kemattil, this is now an approved feature extension.