simplify TranslationalSymmetry: it now takes 1d vectors as parameters directly

doc/source/images/1-quantum_wire.py.diff

doc/source/images/2-ab_ring.py.diff

doc/source/images/2-quantum_well.py.diff

doc/source/images/5-superconductor_transport.py.diff

doc/source/tutorial/1-quantum_wire.py

doc/source/tutorial/1-quantum_wire_revisited.py

doc/source/tutorial/2-ab_ring.py

doc/source/tutorial/2-quantum_well.py

doc/source/tutorial/2-spin_orbit.py

doc/source/tutorial/3-band_structure.py

doc/source/tutorial/4-graphene.py

doc/source/tutorial/5-superconductor_band_structure.py

doc/source/tutorial/5-superconductor_transport.py

doc/source/tutorial/tutorial1.rst

doc/source/tutorial/tutorial4.rst

doc/source/whatsnew/0.2.rst

kwant/builder.py

kwant/graph/tests/test_slicer.py

kwant/lattice.py

kwant/physics/tests/test_noise.py