Merge branch 'feature/mesh-variant' into 'develop'

CMakeLists.txt

src/mesh/MeshFlatEdgeBoundary.cpp

src/mesh/MeshFlatEdgeBoundary.hpp

src/mesh/MeshFlatFaceBoundary.cpp

src/mesh/MeshFlatFaceBoundary.hpp

src/mesh/MeshFlatNodeBoundary.cpp

src/mesh/MeshFlatNodeBoundary.hpp

src/mesh/MeshLineEdgeBoundary.cpp

src/mesh/MeshLineEdgeBoundary.hpp

src/mesh/MeshLineFaceBoundary.cpp

src/mesh/MeshLineFaceBoundary.hpp

src/mesh/MeshLineNodeBoundary.cpp

src/mesh/MeshLineNodeBoundary.hpp

src/scheme/AcousticSolver.cpp

src/scheme/HyperelasticSolver.cpp