BUG-FIX: unsafe storage of halos on petsc_csr_matrix. Only a pointer to the  passed in halo was stored in the allocate routines, which means that the halo  would be invalidated if the halo is deallocated before the matrix.
BUG-FIX: unsafe storage of halos on petsc_csr_matrix. Only a pointer to the 
passed in halo was stored in the allocate routines, which means that the halo 
would be invalidated if the halo is deallocated before the matrix.

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