title: Keyword argument aliases
body: <p>What's a good way to allow aliases for keyword arguments. Say I want an interface like this:</p>
  
  <pre><code>function f(a, b; k1=1, k2=2)
      println(a, b)
      println(k1, k2)
  end
  
  function f(a, b; key1=1, key2=2)
      println(a, b)
      println(key1, key2)
  end
  
  function f(a, b; kw1=1, kw2=2)
      println(a, b)
      println(kw1, kw2)
  end
  
  function f(a, b; keyword1=1, keyword2=2)
      println(a, b)
      println(keyword1, keyword2)
  end
  </code></pre>
  
  <p>so you could call <code>f(1, 2, kw1=3, kw2=4)</code> or <code>f(1, 2, keyword1=3, keyword2=4)</code> and run the same function.</p>