Qulacs

What's Changed
* Fix memory leak in composite gates by corryvrequan in https://github.com/qulacs/qulacs/pull/293
* Bugfix for density matrix tensor product by corryvrequan in https://github.com/qulacs/qulacs/pull/300
* Fix memory leak when creating a quantum operator by kwkbtr in https://github.com/qulacs/qulacs/pull/306
* Fix a bug in the calculation of expectation values on odd-number Pauli-Y observable for density matrix by corryvrequan in https://github.com/qulacs/qulacs/pull/315
* Change file encoding from ShiftJIS to UTF-8 by kwkbtr in https://github.com/qulacs/qulacs/pull/307
* Update version strings to 0.3.1 by kwkbtr in https://github.com/qulacs/qulacs/pull/316
* v0.3.1 by kwkbtr in https://github.com/qulacs/qulacs/pull/317


**Full Changelog**: https://github.com/qulacs/qulacs/compare/v0.3.0...v0.3.1

What's Changed
* Replace the way to cite in README by y-yu in https://github.com/qulacs/qulacs/pull/272
* Back-port the cite way change to dev branch by y-yu in https://github.com/qulacs/qulacs/pull/273
* Update readme with correct build command by corryvrequan in https://github.com/qulacs/qulacs/pull/274
* Disable some options when the target arch. is not x86 by r-imai-quantum in https://github.com/qulacs/qulacs/pull/277
* Fix: ignore trailing whitespaces in Pauli string. by r-imai-quantum in https://github.com/qulacs/qulacs/pull/258
* Move OpenMP parallel directives of get_expectaiton_value by kosukemtr in https://github.com/qulacs/qulacs/pull/247
* Add feature of several density matrix controls by corryvrequan in https://github.com/qulacs/qulacs/pull/283
* Fix pauli operator get expection value by kotamanegi in https://github.com/qulacs/qulacs/pull/276
* Add light partial trace by corryvrequan in https://github.com/qulacs/qulacs/pull/285
* Update SIMD options by corryvrequan in https://github.com/qulacs/qulacs/pull/286
* Update version string to 0.3.0 by r-imai-quantum in https://github.com/qulacs/qulacs/pull/289
* v0.3.0 by r-imai-quantum in https://github.com/qulacs/qulacs/pull/288

New Contributors
* r-imai-quantum made their first contribution in https://github.com/qulacs/qulacs/pull/277

**Full Changelog**: https://github.com/qulacs/qulacs/compare/v0.2.0...v0.3.0

New features & Updates
- Add description about AVX2 in README (241, thanks to y-yu and kwkbtr)
- Add new gate `gate::CP` and `gate::ProbabilisticInstrument` to represent general maps (243 250, thanks to corryvrequan)
- Renew out-dated build guideline in REAMDE (246, thanks to kotamanegi)
- Add fast simulator for noisy circuit (249, thanks to kotamanegi)
- Add concatenate, permutate, and drop qubits in quantum state (245, thanks to corryvrequan)
- Update pybind11 and eigen (253 corryvrequan and 248, thanks to kotamanegi)
- Improve the performance of single-qubit diagonal gate, `Pauli` gate, and `PauliRotation` gate (253, thanks to corryvrequan)
- Move from TravisCI to GitHub Action and resolve wheelbuild issues (256 260 261 263 262 265 266, thanks to y-yu and kwkbtr)
Bug fixes
- Fix a problem that copied parametric circuit does not work (239, thanks to corryvrequan)
- Fix a problem that load function from GPU to CPU does not copy measurement history (242, thanks to corryvrequan)
- Fix double-free issue in parametric gate (244, thanks to corryvrequan and kosukemtr)
- Fix a memory leak in adding a Pauli operator to an observable (251, thanks to corryvrequan)
- Fix a bug in thread-number control (252, thanks to corryvrequan)

This is a hot-fix release that fixes an issue on download URL of eigen (236).
Please also see [v0.1.10 release note](https://github.com/qulacs/qulacs/releases/tag/v0.1.10).

New features & Updates

- Choose random seed for sampling from state (205, thanks to corryvrequan)
- Add argument names and docstrings (209, thanks to corryvrequan)
- Remove `sudo: false` to use Linux infrastructure (206, thanks to y-yu)
- Add support for override of compiler optimization flags (214, thanks to kwkbtr)
- Further SIMD optimization and thread number optimization for Pauli operations (219, thanks to corryvrequan)
- Add Toffoli and Fredkin (220, thanks to corryvrequan)
- Add diagonal gate (221, thanks to corryvrequan)
- Remove experimental qasm load function (223, thanks to corryvrequan)
- Build sdist, bdist_wheel on CI and publish them to PyPI (233, thanks to kwkbtr)
- Add CONTRIBUTING.md (207, thanks to y-yu)

Bug fixes

- Bugfix of bitstring sampling for density matrix (204, thanks to corryvrequan)
- Fix C++ gradient computing coefficients (208, thanks to corryvrequan)
- Fix compiler specification in setup.py to respect environment variables (216 and 229, thanks to kwkbtr)
- Fix Dockerfile (225, thanks to FullteaOfEEIC)
- Fix some commutation properties (232, thanks to akpc)
- Fix typo in example code of PauliOperator (228, thanks to 5c0t-qi)

New features & Updates
* Tutorial update (191, thanks to corryvrequan )
* Implementation on specifying and switching multiple GPUs (194, thanks to puyokw )
* Add a function of multiplying diagonal matrix with python function (197, thanks to puyokw )



Bug fixes
* Check AVX2 support in build script (187, thanks to corryvrequan )
* Apply C++14 flag also for gcc-8 (189, thanks to corryvrequan )
* Add stdio.h include for avoiding Mac OS bugs (190, thanks to corryvrequan )
* Bugfix of projection test (192, thanks to corryvrequan )
* Bugfix for GPU with small targets and many controls (196, thanks to corryvrequan )
* Add `set -o pipefail` to fail CI when failing tests (200, thanks to y-yu )
* Bugfix in trace preserving noise (202, thanks to corryvrequan )