title: Signal when an item is added or removed to a QListWidget
body: <p>I dynamically add and remove items to a QListWidget based on user selections elsewhere in the application. Is there a signal that is emitted when items are added or removed to a QListWidget? The <a href="http://doc.qt.io/qt-4.8/qlistwidget.html#signals" rel="nofollow">signals</a> that I see in the documentation doesn't mention anything for Add or Remove. The rest of the signals are for when individual items are interacted with. </p>
  
  <p>How can I be notified when an item is added to my QListWidget?</p>
  
  <p>A very simple example:</p>
  
  <pre><code>from PyQt4.QtGui import *
  import sys
  
  app = QApplication(sys.argv)
  listWidget = QListWidget()
  
  for i in range(10):
      item = QListWidgetItem("Item %i" % i)
      listWidget.addItem(item)
      # ^^^ This is what I want a signal on
  
  listWidget.show()
  sys.exit(app.exec_())
  </code></pre>
  
  <p>What signal can I utilize to capture that <code>addItem</code> event?</p>