Slightly modify the interface of Circulation and Preflow (#266)
in order to synchronize them to the interface of NetworkSimplex.

Circulation:
- The "delta" notation is replaced by "supply".
- lowerCapMap(), upperCapMap() are renamed to lowerMap() and upperMap().
- Value is renamed to Flow.

Preflow:
- Value is renamed to Flow.

 INCLUDE_DIRECTORIES(

   ${CMAKE_SOURCE_DIR}

   ${CMAKE_BINARY_DIR}

 )

 LINK_DIRECTORIES(${CMAKE_BINARY_DIR}/lemon)

 SET(DEMOS

   arg_parser_demo

   graph_to_eps_demo

   lgf_demo)

 FOREACH(DEMO_NAME ${DEMOS})

   ADD_EXECUTABLE(${DEMO_NAME} ${DEMO_NAME}.cc)

   TARGET_LINK_LIBRARIES(${DEMO_NAME} lemon)

 ENDFOREACH(DEMO_NAME)