Clean up mousemove handler and remove unused tooltip code

public/js/icinga/events.js

@@ -699,6 +699,7 @@
             $(document).off('mouseenter', 'li.dropdown', this.dropdownHover);
             $(document).off('mouseleave', 'li.dropdown', this.dropdownLeave);
             $(document).off('click', 'div.tristate .tristate-dummy', this.clickTriState);
+            $(document).off('mousemove');
         },
 
         destroy: function() {

public/js/icinga/ui.js

@@ -10,9 +10,6 @@
 
     'use strict';
 
-    // The currently hovered tooltip
-    var tooltip = null;
-
     // Stores the icinga-data-url of the last focused table.
     var focusedTableDataUrl = null;