Use hack_p_level inside set_p_level
Use hack_p_level inside set_p_level

This incorporates the hack_p_level assertion and so we no longer have a
way to lose consistency between p_refinement_flag and p_level

libMesh/libmesh,BalticPinguin/libmesh,dschwen/libmesh,dschwen/libmesh,dschwen/libmesh,libMesh/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,dschwen/libmesh,libMesh/libmesh,libMesh/libmesh,dschwen/libmesh,jwpeterson/libmesh,libMesh/libmesh,jwpeterson/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,libMesh/libmesh,dschwen/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,libMesh/libmesh,BalticPinguin/libmesh,libMesh/libmesh,dschwen/libmesh,dschwen/libmesh,jwpeterson/libmesh