Merge branch 'MPL_SaturationExponential' into 'master'

...property/SaturationExponential/c_SaturationExponential.md

...e/properties/property/SaturationExponential/t_exponent.md

...rty/SaturationExponential/t_maximum_capillary_pressure.md

...operty/SaturationExponential/t_residual_gas_saturation.md

...rty/SaturationExponential/t_residual_liquid_saturation.md

MaterialLib/MPL/CreateProperty.cpp

...pillaryPressureSaturation/CreateSaturationExponential.cpp

...CapillaryPressureSaturation/CreateSaturationExponential.h

...ies/CapillaryPressureSaturation/SaturationExponential.cpp

...rties/CapillaryPressureSaturation/SaturationExponential.h

MaterialLib/MPL/Properties/CreateProperties.h

MaterialLib/MPL/Properties/Properties.h

Tests/MaterialLib/TestMPLSaturationExponential.cpp