Added A W S D key events, added classes for Left, Right, Top, Down

Added key events for A W S D - used frequently by gamers instead of arrow buttons.

Added classes to be clicked for calling Left, Right, Up and Down floors (Helps when using with swipe gestures using swipeTouch.js plugin and else way too).

To create left button, use class 'ascensorName'+LinkLeft"

To create right button, use class 'ascensorName'+LinkRight"

To create up button, use class 'ascensorName'+LinkUp"

To create down button, use class 'ascensorName'+LinkDown"

Fucntions added in minified version:

kr() --> right();
kl() --> left();
ku() --> up();
kd() --> down();

Demo at [programofreaks](http://programofreaks.com/test/web) (Try A W S D and swiping with mouse/on touch device)