DoFRenumbering::Cuthill_McKee failed in parallel when a processor had no dofs.
Add a testcase.
Merge pull request #284 from bangerth/fix-cuthill-mckee-without-dofs

Fix cuthill mckee without dofs
clarify documentation of ConstraintMatrix::distribute(VECTOR)

This came up as a question on the mailing list so we should be more precise.
Merge pull request #285 from tjhei/documentation

clarify documentation of ConstraintMatrix::distribute(VECTOR)
Cleanup file of news, added one contribution
Merge pull request #286 from kronbichler/master

Cleanup file of news, added one contribution
made refine_and_coarsen_optmise easier to read and less error prone
Merge pull request #287 from davydden/refinement_optimized

refine_and_coarsen_optmise