Derivative Gridfunction corrected

src/amdis/Assembler.hpp

src/amdis/ProblemStat.hpp

src/amdis/common/TupleUtility.hpp

src/amdis/gridfunctions/AnalyticGridFunction.hpp

src/amdis/gridfunctions/ConstantGridFunction.hpp

src/amdis/gridfunctions/DOFVectorView.hpp

src/amdis/gridfunctions/DerivativeGridFunction.hpp

src/amdis/gridfunctions/FunctorGridFunction.hpp

test/TupleUtilityTest.cpp