maxNodeId() and maxEdgeId() changed to maxId(Node) and maxId(Edge)
getNodeObserverRegistry() and getEdgeObserverRegistry() changed to
getObserverRegistry(Node) and getObserverRegistry(Edge)

IdMappableGraphExtender erased

c LEMON max flow problem

p max 7 9

n 1 s

n 7 t

a 1 2 3

a 1 3 2

a 1 4 1

a 2 5 3

a 3 5 2

a 3 7 5

a 3 6 3

a 4 6 1

a 5 7 2

a 6 7 4