remove unused import
fix possibly misleading error message
add simple test that would break (along with 4 other more complicated tests) if we change the order we do things
Infer: fix potential ordering bug that would show up if we change the order we do things
Rule.Monad.run gets handleFires rather than handleFire
Apply rule handles unifies once, ~3% speedup for euler1
remove Apply rule links also on Trigger.IsTheParameterRef