change return-type of make functions from shared_ptr to unique_ptr

src/amdis/FileWriter.hpp

src/amdis/LocalAssembler.hpp

src/amdis/LocalOperator.hpp

src/amdis/ProblemStat.inc.hpp

src/amdis/QuadratureFactory.hpp

src/amdis/linear_algebra/DOFMatrixBase.inc.hpp

src/amdis/linear_algebra/DOFVectorBase.inc.hpp