New Features
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* `DiscreteQuadraticModel` and `SampleSet` now use the same underlying variable representation. 772, 779
* `DiscreteQuadraticModel.add_linear_equality_constraint` method. 774, 787, 798
* `AdjVectorBQM.add_linear_equality_constraint` method. 784
* Samplers now swallow unknown keyword arguments. 796, 799
* `SpinReversalTransformComposite` no longer requires a structured sampler. 802
Fixes
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* Stopped using deprecated methods and functions to reduce the number of deprecation warnings. 773
* `DiscreteQuadraticModel.copy()` now works correctly. 777
* Fix handling of integer-valued floats in Variables. 779
* Fix the `cyDiscreteQuadraticModel.dtype` setting. 783