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.

 prefix=@prefix@

 exec_prefix=@exec_prefix@

 libdir=@libdir@

 includedir=@includedir@

 Name: @PACKAGE_NAME@

 Description: Library of Efficient Models and Optimization in Networks

 Version: @PACKAGE_VERSION@

 Libs: -L${libdir} -lemon

 Cflags: -I${includedir}