Added Setup::names() and Setup::variables().
Removed [Atom|Literal]::AppendActions().

Not used anywhere.
Added [Ewff|Conj]::And().

Perhaps ewffs should be restricted to conjunctions for simplicity.
Added Clause::ResolveWithUnitClause().

Follows the idea to avoid grounding as long as possible.
Started Setup::PropagateUnits().
Result of Term::Unify() is commutative now.

It always prefers the `smaller' variable.
Ewff representation is closer to unique.

The equality constraints on variables are ordered now.