Improve the function-type interface of bfs, dfs, and dijkstra (ticket #96)
- BfsWizard and DfsWizard have run(s), run(s,t), and run() functions,
DijkstraWizard has run(s) and run(s,t) functions.
- Set NodeMap<T> instead of NullMap as PredMap and DistMap in the default
traits classes for the function-type interface.
- Modify the related test files.
- Doc improvements.
- Bug fix in concepts/path.h.

 INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR})

 ADD_LIBRARY(lemon

   arg_parser.cc

   base.cc

   color.cc

   random.cc)

 INSTALL(

   TARGETS lemon

   ARCHIVE DESTINATION lib

   COMPONENT library)

 INSTALL(

   DIRECTORY . bits concepts

   DESTINATION include/lemon

   COMPONENT headers

   FILES_MATCHING PATTERN "*.h")