Ref issue #332

Add optional parameter to goToSlide, nextSlide, prevSlide, nextPage,
prevPage which accepts an integer which represents the animation
duration in milliseconds.
 Animation locks on update during slide

When an automatic slide is ongoing and update is called, the slider
locks up. Ref issue #337
Added minified version
Merge branch 'issue/332'
v1.3.43

Ability to set animation speed by parameter in public navigation
methods. Animation locks on update during slide. Ref issue #332, #337