Bugfix: funny behavior after window resize due to faulty menu reset

This should fix #154 (and #144). 
Whenever a window resize was made while one menu item was opened, the ``resetMenu()`` would not receive the proper context, subsequently any reset opeeration there would not be executed. Afterwards, the "toggling" would end up being inverted - hiding on mouseenter and showing on mouseleave.

Also, I'm cancelling any handler on ``.item-ul-li`` before they are recreated, as I've noticed some funky things in Chrome which seemed to point to the fact that they are piling up with each window resize.