menu closes on mouseout after 500 ms
clean up default options, add option for closeAfterMove to close after mouse is moved off the menu
adjust menu position if it will be clipped by window edge
added beforeShow callback option to allow for enabling/disabling menu items right before the menu is displayed
needed a way for beforeShow() call back to reference clicked element that prompts the context menu to show
intelligent positioning so context menu doesn't extend past window boundaries