Slide jquery con frecce sempre visibili

[Xinod]

a occhio, cambia
currentPosition = ($(this).attr('id')=='rightControl') ? currentPosition+1 : currentPosition-1;
in

currentPosition = ($(this).attr('id')=='rightControl') ? 
  ((currentPosition==numberOfSlides-1)?0:currentPosition+1) :
  ((currentPosition==0)?numberOfSlides:currentPosition-1);

poi rimuovi
// Hide / show controls
manageControls(currentPosition);
e
// manageControls: Hides and Shows controls depending on currentPosition
function manageControls(position){
// Hide left arrow if position is first slide
if(position==0){ $('#leftControl').hide() } else{ $('#leftControl').show() }
// Hide right arrow if position is last slide
if(position==numberOfSlides-1){ $('#rightControl').hide() } else{ $('#rightControl').show() }
}

ciao