Merge branch 'strain_dependent_permeability' into 'master'

...ainDependentPermeability/c_StrainDependentPermeability.md

...e/properties/property/StrainDependentPermeability/t_b1.md

...e/properties/property/StrainDependentPermeability/t_b2.md

...e/properties/property/StrainDependentPermeability/t_b3.md

...rty/StrainDependentPermeability/t_initial_permeability.md

...rty/StrainDependentPermeability/t_maximum_permeability.md

...rty/StrainDependentPermeability/t_minimum_permeability.md

Documentation/bibliography/ogs.bib

MaterialLib/MPL/CreateProperty.cpp

MaterialLib/MPL/Properties/CreateProperties.h

...lLib/MPL/Properties/CreateStrainDependentPermeability.cpp

...ialLib/MPL/Properties/CreateStrainDependentPermeability.h

MaterialLib/MPL/Properties/StrainDependentPermeability.cpp

MaterialLib/MPL/Properties/StrainDependentPermeability.h

MaterialLib/MPL/VariableType.cpp

MaterialLib/MPL/VariableType.h

Tests/MaterialLib/TestStrainDependentPermeability.cpp