pytket v1.6.1 release

Merge pull request #517 from CQCL/release/1.6.1

Release/1.6.1

pytket v1.6.0 release

Merge pull request #508 from CQCL/release/1.6.0

pytket v1.6.0 release candidate 2

ToffoliBox Synthesis (#494)

* Add first ToffoliBox implementation

* add toffolibox type with minor optimisations

* further improvements

* Update Boxes.cpp

* fix compilation issues

* Fix compilation issues

* Compilation working suitably, with iterators retrieved once

* issues with merging cycles

* Mkae inimum version

* expose to pytket

* black formatting

* update how transpositions found

* add comments with matrices

* Fix issues

* Update circuit_test.py

* Update Boxes.hpp

* Make changes in line with review

* Update Boxes.hpp

* Change to copy constructor

* format

* Update changelog.rst

pytket v1.6.0 release candidate 1

v1.6.0rc1

Use tkwsm version 0.2.0 (#500)

pytket v1.6.0 release candidate 0

v1.6.0rc0

Squash TK1s after KAK (#499)

pytket v1.5.2 release

Merge pull request #496 from CQCL/release/1.5.2

Release/1.5.2

pytket v1.5.1 release

Merge pull request #483 from CQCL/release/1.5.1

Release/1.5.1

pytket v1.5.1 release

[bugfix] Valid TK2 rejected by `in_weyl_chamber` (#480)

pytket v1.5.0 release

Merge pull request #472 from CQCL/release/1.5.0

Release/1.5.0

pytket v1.4.3 release

Merge pull request #453 from CQCL/hotfix/1.4.3

Hotfix/1.4.3