Try appending to a VariableGroup in add_variables
Try appending to a VariableGroup in add_variables

@fdkong ran into a case where adding two variable arrays in MOOSE gave
him false from has_blocked_representation(), apparently because MOOSE
arrays use the libMesh add_variables() API and that API doesn't do the
same variable group optimization that add_variable() does.  Let's try
fixing that.

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