New heuristics for MCF algorithms (#340)
and some implementation improvements.

- A useful heuristic is added to NetworkSimplex to make the
initial pivots faster.
- A powerful global update heuristic is added to CostScaling
and the implementation is reworked with various improvements.
- Better relabeling in CostScaling to improve numerical stability
and make the code faster.
- A small improvement is made in CapacityScaling for better
delta computation.
- Add notes to the classes about the usage of vector<char> instead
of vector<bool> for efficiency reasons.

 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)