Another speed tweak in the unifier
Another speed tweak in the unifier

Don't reduce unless we really have to! Lots of constraints are just
easily sovled equalities between variables, we can reduce if necessary
later.

darcs-hash:20080319154801-974a0-e1560a24139f00a5e5a4250ee989accf86d50910.gz

avsm/Ivor,avsm/Ivor