fix #17 : Scan a folder which has many files makes script crash due to exceed php max time duration.
fix #18 : When user click twice or more than once on start, do a stop before start another to avoid multiple instance of start.
close #19 : When user click on start button, lunch immediately the getRandomPic script and then set the interval.
fix #20 : Hidden folder in pic folder makes the getRandomPic script crash.
close #12 : add a pause button.
(#13) : ESC key pressed do a stop. SPACE key pressed do a pause.
close #8 and close #7: Set Style to picture view and Set style to the options.