Main change is addition of missing interfaces for MFront internal variables extrapolation. Tested on a two-material model with internal states (same as for SmallDeformation).
First two commits handle two additional issues:
Fix possible bug in state s0 initialization of material properties for MFront
Exclude some computations in constitutive relations update and in Ehlers solid material model for initial (dt=0) case. This is temporary measure and requires splitting of the residuum and jacobian contributions.