title: breeze.plot does not compile but works in REPL
body: <p>I tried the sample code in 
  <a href="https://github.com/scalanlp/breeze/wiki/Quickstart" rel="nofollow">https://github.com/scalanlp/breeze/wiki/Quickstart</a></p>
  
  <p>It works when I use a scala console, but in the IDE, it gets a compilation error</p>
  
  <pre><code>p += plot(x, x :^ 2.0)
  </code></pre>
  
  <p>type mismatch; found : Unit required: breeze.plot.Series</p>
  
  <p>is plot only meant to work in the console? Or is there something I can do to make the code compile?</p>