small errors in Arh3Reader/ rh3Writer corrected and ProblemStat::initialize modified to allow bahavior as in previous versions, for expressions::functors a degree mapper was added and the BlockMapper now is initialized with the correct number of components

extensions extended by unit-vector/-matrix; FixVec,Vector and Matrix corrected and extended; lots of other changes

merge from linearAlg-branch. my parallelization needed a slightly more general linear solver interface and uses the pvd-naming scheme from the petsc-parallelization

bug fix for serial petsc solver and workaround to get Rosenbrock working in parallel (but inefficient)

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