function gotoSlide(slide_index) {
    slide_index %= $slides.length
    var $oldslides = $slideshow.children('*')
    $slidebuttons.removeClass('activeButton')
    $slidebuttons.eq(slide_index).addClass('activeButton')
    $slideshow.append($slides.eq(slide_index).clone())
    var $newslide = $slideshow.children('*:last')
  .css('opacity', 0.0)
  .animate({ opacity: 1.0 }, { duration: 500,
      complete: function() {
          $oldslides.remove()
      } 
  })
    current_slide_index = slide_index
}
function slideSwitch() { gotoSlide(current_slide_index + 1) }

function stop() {
    clearInterval(playSlideshow)
    $('#pauseButton').hide()
    $('#playButton').show()
    playSlideshow = null
}
function start() {
    stop()
    playSlideshow = setInterval(slideSwitch, 5500)
    $('#pauseButton, #playButton').toggle()
}