In setupSlides don't want to compare each slide with this.current tosee if display should be set to none or not? Else no slides are hidden (set to display 'none') when you call setup() after add slides (dynamically or whatever). So, display should be set to none if slide != this.current
Allow duration of 0ms

When using the transition 'none' (for instant slide changes), navigating is blocked for the specified duration (it's still 'transitioning'). The workaround would be to use 1ms, but this is more intuitive (you DID set the duration).
Fixed onComplete loop with fadeThroughBackground.

Previously, an onComplete event was added to the previous slide's
tween instance every time the transition wass called.
This stack an additional event every time the effect played,
and created an endless event loop after the first full slideshow cicle.
This has been fixed by removing the event once it has been fired.