Reify failure.
Make-assignment now uses the variables from the CSP.
Don't need assignment-copy for the time being.
Use the CSP-keyed make-assignment.
Define the CSP in terms of domains, constraints, neighbors.
Remove tests for `complete?'.
Select-unassigned-variable
Order-domain-values
Consistent?
Inference
Remove the old definition of CSP.
Actually do constraint satisfaction (inchoate).
Csp-graph -> csp-neighbors
Test backtracking-search.