Psy.Loop should have a Psy.Step as a child

[maartenuni]

Currently, using Psy.Loops, you have to connect to the Loop::iteration signal in order to do something, or override the loop.iteration virtual function in a derived class. This works, but it isn't so nice as Steps, typically activate other steps.
So It would be nice to be able to create a single step/child property of loop. Than on each iteration of the loop, that sub step can be activated and when leaving the substep, you can cause a new iteration of the loop. This way it should be possbile to put new steps inside of a Loop and run the step on each iteration of the loop.