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(FindPackageHandleStandardArgs)

FIND_PROGRAM(GHOSTSCRIPT_EXECUTABLE

  NAMES gs gswin32c

  PATHS "$ENV{ProgramFiles}/gs"

  PATH_SUFFIXES gs8.61/bin gs8.62/bin

  DOC "Ghostscript: PostScript and PDF language interpreter and previewer."

)

FIND_PACKAGE_HANDLE_STANDARD_ARGS(Ghostscript DEFAULT_MSG GHOSTSCRIPT_EXECUTABLE)