Qlazy

- add function(c/py): cu1,cu2,cu3
- add example(py): holevo
- bug fix(py): Densop class - mix

- add function(py): DensOp class - spectrum
- add function(py): DensOp class - entropy,cond_entropy,mutual_info,relative_entropy
- add example(py): trace distance, entropy

- add example(py): fidelity
- add function(py): DensOp class - fidelity,distance

- add function(c/py): qstate_init, QState.__new__ (create from a vector)
- add example(py): Schmidt decomposition

- add function(py): Densop.instrument
- add function(py): Densop.expect
- add function(c): swap gate (sw)
- add function(py): swap gate (sw), fredkin gate (csw)
- add function(c/py): U1,U2,U3 gate (u1,u2,u3)
- change spec(py): Densop.__new__
- change spec(c): densop_probability,densop_apply_matrix
- change spec(py): DensOp.probability,DensOp.apply
- bug fix(c/py): densop_sqtrace, DensOp.sqtrace
- refactoring(c): qstate,gbank,...
- add example(py): QChannel/amplitude_dumping.py

- update(doc): Tutorial_py.md - DensOp class
- bug fix(c/py): densop_apply_matrix, DensOp.apply
- change spec(c): qstate_apply_matrix
- add function(c) densop_add,densop_mul,densop_measure_kraus,densop_measure_povm
- add function(py) DensOp.add,DensOp.mul,DensOp.measure,DensOp.mix
- add function(c/py): densop_get_amp, DensOp.get_amp
- add example(py): Measure/povm.py