Added News Slideshow portal mode

* new portal mode merged from News Show Pro GK4
* interface recreated with CSS pseudo elements (graphics files totally
removed)
* changes in gk.thumbs.php to avoid Strict Standard messages related
with static funcitons
* Portal mode structure clean up and animations attributes output using
data-* attributes
* Small changes in engine - periodically() replaced by setInterval()
* jQuery version of portal mode engine