Summary:
Closes T2507.

For more convenient testing and debugging of material laws, the `MaterialEvaluator` class encapsulates a an object of a `MaterialBase` daughterclass and allows to evaluate the stress-strain relationship as well an the analytical tangent moduli and a numerical approximation of said tangent.

WIP: started MaterialEvaluator

first functional material evaluator, tested

ENH: Material evaluator can now estimate tangent numerically

WIP: switching to non-templated material evaluators

ENH: material evaluator no longer templated my the material

Merge branch 'master' into feat/material_evaluator_T2507

WIP: writing python bindings for material evaluator

ENH: Material Evaluator now has python bindings

BUG: Missing test of material evaluator added

BUG: flush Jenkins's pybind11

BUG: undo the jenkins flush

WIP: documenting and wrapping up material evaluator

ENH: material evaluator documented

Test Plan: ci passes

Reviewers: RLeute, afalsafi

Reviewed By: RLeute, afalsafi

Maniphest Tasks: T2507

Differential Revision: https://c4science.ch/D234