Removed early check that cand term has variables.
true(false)_of_unit is now in lib, enjoy.
LSD: transition predicates now conditional.
Merge pull request #197 from AdrienChampion/invGen-optimization

Improved candidate term generation scalability
Construct negative rationals with minus operator
Merge pull request #198 from chsticksel/develop

Construct negative rationals with minus operator
Merge remote-tracking branch 'upstream/develop' into invGen-conditional-trans