Fix for parallel strong scalar bcs in parallel for the case where all owned nodes in a domain are on the strong bc boundary.
Fix for parallel strong scalar bcs in parallel for the case where all owned nodes in a domain are on the strong bc boundary.

This might fix the hangs in square-convection-parallel-trivial (it fixes at least some of them).

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