title: Multiple font sizes in plot title
body: <p>I'm plotting in an IPython IDE using <code>Matplotlib.pyplot</code> and added a title with:</p>
  <pre class="lang-py prettyprint-override"><code>plt.title('Mean WRFv3.5 LHF\n(September 16 - October 30, 2012)', fontsize=40)
  </code></pre>
  <p>However, I want the first line to be size 40 and the second line to be size 18.  Is that possible in <code>matplotlib</code>?  I saw the LaTeX use of <code>\tiny</code> and <code>\Huge</code>, but would like more control.</p>