add-quadratic-from-52f923c89ce762cb.yaml

---
features:
  - |
    Add an abstract method ``QuadraticViewsMixin.add_quadratic()``.
  - |
    Add a method ``QuadraticViewsMixin.add_quadratic_from()`` to add quadratic
    interactions. This method is intended to be used as follows:
    ``ConstrainedQuadraticModel.objective.add_quadratic_from()``, similarly to
    ``ConstrainedQuadraticModel.objective.add_linear_from()``.
upgrade:
  - |
    All sublcasses of ``QuadraticViewsMixin``, including ``ObjectiveView``, 
    ``QuadraticModel`` and ``BinaryQuadraticModel``, now require to have 
    the method ``add_quadratic()``.