title: Expression of italics and superscripts in ggplot axis title
body: <p>I am sorry to ask this, but I can't seem to get this expression right to include in the <code>ylab()</code> or <code>xlab()</code> arguments of a ggplot2-object. It needs to read:</p>
  
  <p>"<em>2q</em> (rarefied)". The "2" needs to superscripted, though.</p>
  
  <p>I have fiddled with <code>expression()</code> and <code>paste()</code>, but it seems impossible. Any help is much appreciated.</p>
  
  <p>edit: Some example:</p>
  
  <pre><code>dat&lt;-as.data.frame(matrix(runif(100), 10,10))
  names(dat) &lt;- LETTERS[1:10]
  
  library(ggplot2)
  ggplot(dat, aes(A,B)) +
    geom_point()+
    xlab("some title")
  </code></pre>