merge from mainline

git-svn-id: https://svn.dealii.org/branches/branch_unify_linear_algebra@29690 0785d39b-7218-0410-832d-ea1e28bc413d

diff --cc deal.II/include/deal.II/lac/petsc_parallel_vector.h
Simple merge

diff --cc deal.II/include/deal.II/lac/trilinos_vector.h
Simple merge

diff --cc deal.II/include/deal.II/lac/trilinos_vector_base.h
Simple merge

diff --cc deal.II/include/deal.II/lac/vector.templates.h
Simple merge

diff --cc deal.II/source/lac/constraint_matrix.cc
Simple merge