Some cleanups an consistency improvements in mps_gen.
Split sandwich into mps and tdvp.
Sync up expectation-value methods.
Update __init__.py
Fix growing and shrinking (update D and q).
Support array Hamiltonian, add overlap to "go" integrato
Manage h_nn during growing and shrinking.
Fix overlap saving in go function.
Remove unneeded code in sandwich go script.
Add _init_arrays() to tdvp_gen. Fix expect_1s() in mps_gen.
Improve Hamiltonian support in tdvp_gen (half-way to three-site branch)
Modernise transverse_ising example a little.
More transverse_ising example improvements. Add tdvp_gen unit test using transverse Ising.
More work on Ising test case and example.
Minimally fix examples.
More minimal fixes.
Add RK4 test of Ising model.
Use array ops and ham in heisenberg uniform example.
Array hams in generic heisenberg example. Now with spin 1!