title: Angular ngbDropdown autoClose outside not working in version 4.1.3
body: <p>I am using ngbDropdown and have upgraded ng-bootstrap from version 3 to 4.1.3, and now [autoClose]="'outside'" is closing, no matter if I press inside or outside the dropdown :-| if I set it to false it's working like expected.</p>
  
  <pre><code>&lt;span *ngIf="!isAllItemsDisplayed"
  ngbDropdown
  #dropdown="ngbDropdown"
  [autoClose]="'outside'"
  [placement]="['right-bottom', 'right', 'right-top']"&gt;
      &lt;i ngbDropdownToggle
          class="icon icon-dots dropright drill-drop"
          [class.inactive]="isAnyActionSelected"&gt;
      &lt;/i&gt;
      &lt;div ngbDropdownMenu *ngIf="dropdown.isOpen()"&gt;
          &lt;p class="drillmenuheader"&gt;{{unit.name | textEllipsis: 12 }}&lt;/p&gt;
          &lt;ov-drilldown-screen-item *ngFor="let drilldown of drilldowns"
              [screen]="drilldown"
              [showLabel]="true"
              (navigate)="navigate($event)"&gt;
          &lt;/ov-drilldown-screen-item&gt;
          &lt;div class="dropdown-divider"*ngIf="isCommandActionsVisible"&gt;&lt;/div&gt;
          &lt;ov-drilldown-action-item *ngFor="let action of actions"
              [action]="action"
              [showLabel]="true"
              [unitId]="unit ? unit.id : 0"
              [unitName]="unit ? unit.name : ''"&gt;
          &lt;/ov-drilldown-action-item&gt;
      &lt;/div&gt;
  </code></pre>
  
  <p></p>
  
  <p>Angular version 7.3.1
  ng-bootstrap version 4.1.3</p>
  
  <p>Anyone has a solution for this issue?</p>
  
  <p>thanks very much in advance :-) </p>