Method name Entity<0>::subEntities(codim) misleading

The name of the subEntities(codim) method on Entity<0,...> returning the number of subentities is misleading. In view of the various range-interfaces that have been introduces, one would expect this one to return a range of subentities. For clarity this should be renamed (with deprecation of the old name for sure). A possible name would be subEntityCount(codim). On the reference elements this is simply called size(codim) which would be nice in view of consistency.