- Feature #945: In SecondPiolaKirchhoffTensor, hyperelastic laws are now stored by reference rather than policy and may be shared with some other parts of the code (required in Poromechanics). Their instantiation is now much more prominent within Operators library: it is no longer hidden within LocalVariationalOperatorInstances. Ongoing tickets: - #820 Poromechanics: implicit step fluid is done; solid step has been begun but currently yields stupid results.