title: Colorize parts of the title in a plot
body: <p>Is it possible to colorize parts of the title in a plot?</p>
  
  <pre><code>x = 1:10
  y = 1:10
  plot(x, y, main="title (slope=1)")
  </code></pre>
  
  <p>In this plot I'd like to change the color of <code>slope=1</code> to red.</p>