Adjacency matrix is by nature bidirectional and one can see that the
concept was mostly implemented before. That implementation missed
the degree function(s). These functions are implemented in this commit
and the traversal_category is updated to meet the concept requirements.
Tests are also added, though they are a bit shallow in the sense that
they seem to omit intensive algorithms.
The initial checkin supports bundled properties for adjacency list,
matrix, undirected and directed graphs, the labeled graph adaptor
and the reverse graph adaptor. All tests updated, passed.
Documentation should be updated, but isn't yet.
[SVN r64645]
