added a function to hide all slides and then show only current, next and prev. Improves performance on iOS.
Added API and options. API freeze/unfreeze enables to programically disable user touch input. There are cases where the user needs to do touch actions on a swipe card (example: selecting text in an input feild). In such cases freezing the card prevents it from "sliding under" the action. Options pastSlideEnd/pastSlideStart/pastResistance enable to set an action that will trigger when the user swipes past the edges of the swiper. This is useful if the swiper takes the whole interface (full screen) as a way to get into and out of the swipe interface.