Added keywords SOF2 and SWFN to allow for different saturation functions.
added keywords FULLIMP and IMPES.
Merge pull request #376 from dr-robertk/PR/add-keyword-FULLIMP-IMPES

added keywords FULLIMP and IMPES.
Merge pull request #375 from dr-robertk/PR/add-keyword-SOF2-SWFN

Added keywords SOF2 and SWFN to allow for different saturation functions.
Added if (BUILD_TESTING) ... around tests.
Changed backtics to single ticks in string literal.
Removed unused Deck argument in method
Merge pull request #377 from joakim-hove/BUILD_TESTING

Build testing