merge of trunk with arhfile2 branch: 'using namespace' removed from header files, file readers/writer moved to subnamespace AMDiS::io, test for arh2writer added

gmres solvers improved: householder orthogonalization added; corrections in sequential PETSc solvers/matrixstreams

 patch for initfiles of periodic and parametric, but dont work. parametric has polynomial degree 2, which is not supported by the arh writers and readers. the arh test checks also the error message with wrong input argument and the comparer uses a higher tolerance of 1e-11 now.. but vecellipt has a difference of 1e-6