changed petsc cmake configuration

added computation of global DOF ids for pre-bases

Global basis ids for dune 2.6 and dune 2.7

corrected the unbind function

wrong unbind function call corrected

Added partition type query to GlobalIdSet

added documentation and extended the test

add general implementation and specialization for TaylorHoodBasis

corrected treepath of velocity component in taylorhoodbasis

add PETSc find module and configuration to cmake

add DofMapping for the association of local and global indices

changed petsc cmake configuration

added DOFMapping and test, to be used with petsc or pmtl backend

extension of istl preconditioner and amg precon

added block jacobi preconditioner with sequential sub precon

update ISTLCommTest for new Communication Creators

removed some smoothers due to bugs in dune-istl

added krylov AMG preconditioner

restructuring of istl solvers and preconditioners

Corrected errors in uniqueBorderPartitionTest a...