Various bug fixes and code improvements in adaptors.h (#67)

- Fix UndirectorBase::nodeNum().
- Fix UndirectorBase::findEdge().
- Fix OrienterBase::addArc().
- Fix OrienterBase::findArc().
- Improve SplitNodesBase::findArc().
- Add missing notifier() function in UndirectorBase.
- Add missing typedefs for maps (conform to the ReferenceMap concept).
- Add some useful typedefs for graph adaptors.

 EXTRA_DIST += \

 	demo/CMakeLists.txt \

 	demo/digraph.lgf

 if WANT_DEMO

 noinst_PROGRAMS += \

 	demo/arg_parser_demo \

 	demo/graph_to_eps_demo \

 	demo/lgf_demo

 endif WANT_DEMO

 demo_arg_parser_demo_SOURCES = demo/arg_parser_demo.cc

 demo_graph_to_eps_demo_SOURCES = demo/graph_to_eps_demo.cc

 demo_lgf_demo_SOURCES = demo/lgf_demo.cc