2.3.0

Semi-bugs/features:

• scale_by_problem_size for path goals now only uses number of active time steps.
• Much improved scaling of initial derivatives.
• Improve branch allocation of ControlTreeMixin.
• Fix inconsistencies in internal API w.r.t. what methods can return symbolic values.

Improved checks:

• Sanity checks on goals, e.g. function ranges. Some models may fail the checks now, but if they do the goal in question did not make much sense anyway.

New features:

• Vector goals (mostly a performance improvement)
• Optional more generic/optimal way of translating goals from current priority to the next. See keep_soft_constraints option added in commit f6eb00d.
• Can now provide a custom (initial) seed to SimulationProblem.
• Allow extra variables to appear in path expressions
• New examples, in particular showing the use (and strength) of using HomotopyMixin for channel flow.
• Many large and small optimizations and refactorings for perform