Entirely rework CostScaling (#180)

- Use the new interface similarly to NetworkSimplex.
- Rework the implementation using an efficient internal structure
for handling the residual network. This improvement made the
code much faster.
- Handle GEQ supply type (LEQ is not supported).
- Handle infinite upper bounds.
- Handle negative costs (for arcs of finite upper bound).
- Traits class + named parameter for the LargeCost type used in
internal computations.
- Extend the documentation.

 SET(LEMON_INCLUDE_DIR "@CMAKE_INSTALL_PREFIX@/include" CACHE PATH "LEMON include directory")

 SET(LEMON_INCLUDE_DIRS "${LEMON_INCLUDE_DIR}")

 IF(UNIX)

   SET(LEMON_LIB_NAME "libemon.a")

 ELSEIF(WIN32)

   SET(LEMON_LIB_NAME "lemon.lib")

 ENDIF(UNIX)

 SET(LEMON_LIBRARY "@CMAKE_INSTALL_PREFIX@/lib/${LEMON_LIB_NAME}" CACHE FILEPATH "LEMON library")

 SET(LEMON_LIBRARIES "${LEMON_LIBRARY}")

 MARK_AS_ADVANCED(LEMON_LIBRARY LEMON_INCLUDE_DIR)