title: "-type truecolorAlpha" does not work
body: <p>I have some images whose type is <code>PaletteAlpha</code> and which have to be <code>TrueColorAlpha</code>. I am trying to use the command </p>
  
  <pre><code>convert testein -type TrueColorAlpha testeou
  </code></pre>
  
  <p>to do this conversion but the result is an image which still has <code>Type: PaletteAlpha</code>. Is this behaviour expected? How can I transform from one type to the other?</p>
  
  <p>I have also tried things such as <code>PNG:testeou</code> but with no results.
  My IM version is <code>6.7.8-9</code>.</p>