Remove unused functions
Added tests for canonical_form() and normal_form() and fixed various typos in those functions, including an obsolete use of where_to_truncate().
Test that scprod() properly reproduces global phases.
Added some explanatory comments in prop_init(), denoting the convention of indices.
scprod() took the real part of its argument.
Test trivial time evolution of MPS with multiples of identity.
Added a constructor (missing but used in the code) for building sparse matrices from raw data
Fixes in the implementation of full() and of the sparse binary operators.
Tests for the sparse binary operations
mps_to_vector() did not work when the bond dimension was = 1
Small cosmetic change in sparse_1d_hamiltonian
Added tests for TimeSolver using local operators (sx and sz)