title: Convert escaped codepoint to unicode character
body: <p>I am trying to take a chunk of JSON that has strings which contain the literal characters <code>\u009e</code> and I would like to convert those characters to its associated single unicode character, in this case <code>é</code>.</p>
  
  <p>I use curl or wget to download the json which looks like:</p>
  
  <pre><code>{ "name": "Kitsun\u00e9" }
  </code></pre>
  
  <p>And need to translate this in Vim to:</p>
  
  <pre><code>{ "name": "Kitsuné" }
  </code></pre>
  
  <p>My first thought was to use Vim's iconv, but it does not evaluate the string as a single character and just returns the input.</p>
  
  <pre><code>let code = '\u00e9'
  echo iconv(code, "UTF-8", "UTF-8")
  " Prints \u00e9
  </code></pre>
  
  <p>I want to eventually use something like</p>
  
  <pre><code>%s;\\u[0-9abcdef]*;\=iconv(submatch(0),"UTF-8", "UTF-8");g
  </code></pre>