add hybrid Roe/Rusanov schemes

src/language/modules/CompositeSchemeOtherFluxesModule.cpp

src/scheme/CMakeLists.txt

...HybridRoeRusanovViscousFormEulerianCompositeSolver_v2.cpp

...HybridRoeRusanovViscousFormEulerianCompositeSolver_v2.hpp

...HybridRusanovRoeViscousFormEulerianCompositeSolver_v2.cpp

...HybridRusanovRoeViscousFormEulerianCompositeSolver_v2.hpp

src/scheme/RoeViscousFormEulerianCompositeSolver_v2.cpp

src/scheme/RusanovEulerianCompositeSolver_v2.cpp