title: Adjust padding inside matplotlib annotation box
body: <p>I'm using the <code>annotate</code> method on an <code>Axes</code> object to add an arrow with text to a plot.  For example:</p>
  
  <pre><code>ax.annotate('hello world,
              xy=(1, 1),
              xycoords='data',
              textcoords='data',
              fontsize=12,
              backgroundcolor='w',
              arrowprops=dict(arrowstyle="-&gt;",
                              connectionstyle="arc3")
  </code></pre>
  
  <p>This works well but I want to decrease the padding on the inside of the annotation box.  Essentially, I want to make the box 'squeeze' tighter around the text.  Is there any way to do this via the <code>arrowprops</code> or <code>bbox_props</code> kwargs?</p>
  
  <p>I'm looking for something like <code>borderpad</code> that's available on legends, similar to what's discussed <a href="https://stackoverflow.com/a/20049202/1108031">on this answer</a>.</p>