Initial commit to this repo.
Overhaul of the graph library.

GRAPH has been split into GRAPH and GRAPH-PATH. The latter has a new Path
sort which preserves the order of the edges. It also fixes a bug in the old
path-finding algorithm, which did not respect the directionality of edges
in the graph (it treated all edges as undirected).

META-GRAPH has been moved to its own file until I can overhaul it.
Got rid of the damned NodePair in GRAPH .

In the EDGE theory, nodes now returns a NodeSet, and a SIMPLE-SET module is
provided for convenience.
Reorganized GRAPH.

Combined GRAPH and GRAPH-PATH. Implemented cycle checking in terms of
findNePath.
Renamed bc-inference to bc-unification.

Also added a definition of replace for UnificandSet.
Added a base-case for replace.
Added BC-GRAPH to bc-unification.maude

Also cleaned up the definitions in QID-EDGE a bit.
Some rearranging.
Added ops for extended path searching.
We new use the dependency graph in bc-infer.
In theory we're done. Testing time!
Caps and unificand fixes.
Lots and lots of work.
Added a test file.
Tweaks and changes.
Started work on the write-up.
All source code licensed and included.
Working more on write-up.
Updated acknowledgements.
Signatures are now automatically extracted.