Merge pull request #13457 from peterrum/distribute_local_to_global_by_interpolation

Allow to average values in parallel::distributed::SolutionTransfer

diff --cc include/deal.II/dofs/dof_accessor.h
Simple merge

diff --cc source/distributed/solution_transfer.cc
Simple merge

diff --cc source/dofs/dof_accessor_set.cc
Simple merge

diff --cc source/dofs/dof_accessor_set.inst.in
Simple merge