Appends the specified Vertex entity to this Polyline entity, and makes this Polyline entity its owner.

Returns the Object ID of the appended vertex. 

If this Polyline entity is database resident, the Vertex entity will be made database resident. 

If this Polyline entity is not database resident, the Vertex entity will be made database resident when this Polyline entity is made database resident.

If this Polyline is database resident, the Vertex entity must explicitly be closed when appendVertex() returns.