title: PyQt: receive QTableWidget column resize signal
body: <p>I'm using PyQt. I want to detect when a user resizes columns in a QTableWidget.</p>
  <p><a href="https://stackoverflow.com/questions/14648999/qtablewidget-column-resize-event">This answer for C++</a> suggests that the signal will be <code>QTableWidget.horizontalHeader.sectionResized</code>, but that gives this error:</p>
  <pre><code>AttributeError: 'builtin_function_or_method' object has no attribute 'sectionResized'
  </code></pre>
  <p>How can I connect in Python to the <code>sectionResized</code> signal?</p>