fixes mutateme.zf.trigger fires as often as many submenu you got because it's...

fixes mutateme.zf.trigger fires as often as many submenu you got because it's in the _events($elem) function, and this gets bound as manu times you got submenues.

i'got a menu with 92 submenu's and wondered why the performance is so weak on clicking on the responsiveToggle, so i started searching an found that the mutateme event gets fired as many times as there are submenus, and on the drilldown then 92 times the _getMaxDims was executedthis calcs the heights and so on and is very performant, so i debugged it an moved it to the _registerEvents function

big performance improvement