Lightbox 2 bugfix

There is a bug in Lightbox 2 slideshow. When an image has no title during slideshow it shows the title of previous or next image title. To fix this problem add in lightbox.js

else{
this.caption.update("").show();
}
after

// if caption is not null
if (this.imageArray[this.activeImage][1] != ""){
this.caption.update(this.imageArray[this.activeImage][1]).show();
}