added more tests and corrected MultiTypeMatrix

dune/amdis/common/Mpl.hpp

dune/amdis/common/MultiTypeMatrix.hpp

dune/amdis/common/MultiTypeVector.hpp

dune/amdis/common/Size.hpp

dune/amdis/common/Tags.hpp

dune/amdis/common/ValueCategory.hpp

dune/amdis/utility/FiniteElementType.hpp

dune/amdis/utility/MultiIndex.hpp

dune/amdis/utility/RangeType.hpp

dune/amdis/utility/Visitor.hpp

test/CMakeLists.txt

test/FiniteElementTypeTest.cpp

test/MultiTypeMatrixTest.cpp

test/RangeTypeTest.cpp

test/TreeDataTest.cpp