collectSBAs now uses View monad
+1/+1 and -1/-1 counters now affect power/toughness
TargetLists now immediately contain EntityRefs; introduced TargetSpecs
Helper function `will'
Renamed mkTriggerObject -> mkTargetTrigger; mkTargetlessTriggerObject -> mkTrigger
Stack items now also receive their controller to determine their resolution effect; further improved targetting/trigger API