on exit menu default active row to null

I have implemented the jquery menu aim on my site's left nav with only hovers and found that it didn't deactivate the menu correctly when exitMenu was called. So I added 'activeRow = null' whenever the mouse leaves the menu to ensure that it always starts the menu functionality fresh when you hover back onto the menu. This might break menus where you click to open - but thought I would submit this anyway for your consideration. Great plugin, really like it!