Make example.pl executable
Arrange so 'gift' can help manage this package
Add unit tests
Use \= rather than \+ ... =
Document why var/1 clause exists

Without this clause, goal_expansion_loop fails when T is a free
variable.  We need it to succeed so that we can expand each argument
of X=n(1,234)
Make cuts green

Make it clearer that each clause is independent of the others.
Add PlDoc documentation
Bump version number