Correctly set up PETSc matrices allocated from sparsities
Correctly set up PETSc matrices allocated from sparsities

When we allocate a PETSc matrix from a Fluidity sparsity, we don't go
through csr2petsc_CreateMPIAIJ (or similar).  So for local assembly to
work we need to set the MAT_IGNORE_OFF_PROC_ENTRIES flag explicitly in
the allocate_petsc_csr_matrix_from_foo routines.

rjferrier/fluidity,jjo31/ATHAM-Fluidity,iakovos-panourgias/fluidity,iakovos-panourgias/fluidity,iakovos-panourgias/fluidity,jjo31/ATHAM-Fluidity,iakovos-panourgias/fluidity,rjferrier/fluidity,rjferrier/fluidity,jrper/fluidity,rjferrier/fluidity,jrper/fluidity,jjo31/ATHAM-Fluidity,rjferrier/fluidity,jrper/fluidity,jjo31/ATHAM-Fluidity,iakovos-panourgias/fluidity,jrper/fluidity,jjo31/ATHAM-Fluidity,jrper/fluidity