Merge pull request #2999 from endJunction/RMPassSolidPressureToDensity

MaterialLib/MPL/VariableType.cpp

MaterialLib/MPL/VariableType.h

ProcessLib/RichardsMechanics/RichardsMechanicsFEM-impl.h

...ardsMechanics/deformation_dependent_porosity_swelling.prj

...n_dependent_porosity_swelling_pcs_0_ts_102_t_3.500000.vtu

...n_dependent_porosity_swelling_pcs_0_ts_107_t_4.000000.vtu

...on_dependent_porosity_swelling_pcs_0_ts_14_t_0.500000.vtu

...on_dependent_porosity_swelling_pcs_0_ts_19_t_1.000000.vtu

...on_dependent_porosity_swelling_pcs_0_ts_33_t_1.500000.vtu

...on_dependent_porosity_swelling_pcs_0_ts_38_t_2.000000.vtu

...on_dependent_porosity_swelling_pcs_0_ts_63_t_2.500000.vtu

...on_dependent_porosity_swelling_pcs_0_ts_88_t_3.000000.vtu