jQuery.hoverDelay improvements

jquery.hoverDelay: On "unhover" verify we are not actually over a child of the hovering context. Additionally added support for "virtual children" (addChildren option), which is useful for things that is absolute positioned but not actually a child of the context. Lastly, made pointerenter and pointerleave work like the rest of the pointy.js polyfill, it will fallback to mouse events automatically for you.