Use _out_of_mesh_value for unknown var indices
Use _out_of_mesh_value for unknown var indices

This gives higher level code more options than "scream and die" when
projecting from one system onto another system with slightly different
variables defined.

roystgnr/libmesh,jwpeterson/libmesh,capitalaslash/libmesh,balborian/libmesh,libMesh/libmesh,dschwen/libmesh,libMesh/libmesh,svallaghe/libmesh,libMesh/libmesh,svallaghe/libmesh,giorgiobornia/libmesh,balborian/libmesh,90jrong/libmesh,roystgnr/libmesh,libMesh/libmesh,hrittich/libmesh,roystgnr/libmesh,giorgiobornia/libmesh,giorgiobornia/libmesh,svallaghe/libmesh,giorgiobornia/libmesh,jwpeterson/libmesh,giorgiobornia/libmesh,90jrong/libmesh,pbauman/libmesh,capitalaslash/libmesh,giorgiobornia/libmesh,dschwen/libmesh,svallaghe/libmesh,90jrong/libmesh,dschwen/libmesh,90jrong/libmesh,90jrong/libmesh,BalticPinguin/libmesh,svallaghe/libmesh,90jrong/libmesh,svallaghe/libmesh,pbauman/libmesh,hrittich/libmesh,jwpeterson/libmesh,hrittich/libmesh,hrittich/libmesh,giorgiobornia/libmesh,libMesh/libmesh,capitalaslash/libmesh,dschwen/libmesh,roystgnr/libmesh,hrittich/libmesh,pbauman/libmesh,pbauman/libmesh,dschwen/libmesh,balborian/libmesh,jwpeterson/libmesh,hrittich/libmesh,pbauman/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,capitalaslash/libmesh,BalticPinguin/libmesh,balborian/libmesh,BalticPinguin/libmesh,pbauman/libmesh,capitalaslash/libmesh,svallaghe/libmesh,jwpeterson/libmesh,libMesh/libmesh,hrittich/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,roystgnr/libmesh,roystgnr/libmesh,balborian/libmesh,svallaghe/libmesh,90jrong/libmesh,jwpeterson/libmesh,capitalaslash/libmesh,libMesh/libmesh,hrittich/libmesh,BalticPinguin/libmesh,balborian/libmesh,jwpeterson/libmesh,dschwen/libmesh,BalticPinguin/libmesh,svallaghe/libmesh,pbauman/libmesh,dschwen/libmesh,dschwen/libmesh,giorgiobornia/libmesh,balborian/libmesh,capitalaslash/libmesh,capitalaslash/libmesh,hrittich/libmesh,pbauman/libmesh,roystgnr/libmesh,balborian/libmesh,90jrong/libmesh,libMesh/libmesh,90jrong/libmesh,giorgiobornia/libmesh,balborian/libmesh,balborian/libmesh,pbauman/libmesh