ReaLearn: Absolute invocation mode + trigger action should be retriggerable

At the moment, they are not. Which means ReaLearn won't invoke the action if it already has the correct value. Sounds good but has a catch: Trigger-like actions (unlike toggle actions) only have ReaLearn-generated "fake" values, because natively, REAPER actions don't have the concept of a *current value*. If that fake value is incorrect, ReaLearn won't fire. Bad.