title: Faceted qqplots with ggplot2
body: <p>Say I have the following data:</p>
  
  <pre><code>datapoints1 = data.frame(categ=c(rep(1, n), rep(2, n)), vals1=c(rt(n, 1, 2), rnorm(n, 3, 4)))
  datapoints2 = data.frame(categ=c(rep(1, n), rep(2, n)), vals2=c(rt(n, 5, 6), rnorm(n, 7, 8)))
  </code></pre>
  
  <p>Using <code>ggplot2</code>, how can I use the <code>facet</code> functionality to create in a single command two QQplots, i.e. one with the two <em>t</em> samples, the other with the two Gaussian samples?</p>