Path related files ported from svn -r3435
but ItemReader/Writer for Path (originally belonging to path_utils.h)
hasn't ported yet.
Doc improvements
Hide and privatize member function funcOption()
Merge path_utils.h into path.h
Digraph and Graph concept should be conform to the IDable... concepts
Array range check warning workaround in random.h

The g++-4.2.1 preferred by OpenSUSE has a bug with array range cheking
Merge
Forbid automake to add superfluous include dirs. Fixes ticket #21.
Several fixes and improvements in list_graph.h.

- Fix incorrect or misleading renamings in the code and in the documentation.
- Improve the documentation.
Minor improvement in groups.dox.
Fix doxygen warnings.
Merge (redo buggy merge ad7f593399b0)
Port error.h from svn -r3438 + minor changes (error_test does not pass!)

In svn -r3438 error_test is not used as a test program and it does not pass.
Merge
Merge
Bfs/Dfs/Dijkstra and their deps ported from svn trung -r 3441.
Some usefull math constants

lemon/math.h also includes the standard cmath, so one should prefer using
just lemon/math.h instead of cmath.
Merge
Fix VPATH builds. Ported form svn trunk -r 3454.
Bug fixes in the ReferenceMap concept.