Finish and Completion order

[zompi2]

Currently every action runs completion events first and then marks the action as finished.
This can lead to a confusing situation, where developer would like to modify the action in the completion event right before it becames invalid.
Logically, in the completion event the action should be marked as finished. It shouldn't be allowed to pause/resume/reset such action at this point.

Please pay attention to what happens when action is finished via RemoveAction with bComplete set to true.