Merge branch 'feature/parallel_istl' into 'master'

src/amdis/LinearAlgebra.hpp

src/amdis/ProblemStat.hpp

src/amdis/ProblemStat.inc.hpp

src/amdis/functions/GlobalIdSet.hpp

src/amdis/linearalgebra/Common.hpp

src/amdis/linearalgebra/LinearSolver.hpp

src/amdis/linearalgebra/LinearSolverInterface.hpp

src/amdis/linearalgebra/PreconditionerInterface.hpp

src/amdis/linearalgebra/RunnerInterface.hpp

src/amdis/linearalgebra/eigen/CMakeLists.txt

src/amdis/linearalgebra/eigen/DirectRunner.hpp

src/amdis/linearalgebra/eigen/IterativeRunner.hpp

src/amdis/linearalgebra/eigen/SolverCreator.hpp

src/amdis/linearalgebra/eigen/Traits.hpp

src/amdis/linearalgebra/istl/CMakeLists.txt

src/amdis/linearalgebra/istl/Communication.hpp

src/amdis/linearalgebra/istl/Communication.inc.hpp

src/amdis/linearalgebra/istl/Creators.hpp

src/amdis/linearalgebra/istl/DirectRunner.hpp

src/amdis/linearalgebra/istl/ISTLRunner.hpp