- Creation of processor-wise GeometricMeshRegion is now much cleaner: it is the global GeometricMeshRegion object that is shrunk to a processor-wise one instead of relying on a file written on disk that was read again. As a consequence, some attributes that were duplicated (support_dof_mesh_ for UnknownVariable and mesh_ for LinearProblem) are now united; they become local as soon as the partitioning is done. Less memory is hence used: the global objects no longer exists, whereas previously they were there for the whole program (and were also used to fetch data; all these call have been replaced by processor-wise ones). - GeometricElement now holds a pointer to the vertice, rather than a mere index. - There was a remaining gather through MpiAllReduce that was completely irrelevant (it was to apply the BC, but only the local dofs were meaningful due to the structure of the matrix after renumbering).