title: The setHex method of PHP MapScript doesn't work
body: <p>I'm using PHP MapScript 6.4 to interact with my Mapfile.
  I try to use the <code>setHex()</code> colorObj method like that:</p>
  <pre><code>$oStyle-&gt;color-&gt;setHex($color);
  </code></pre>
  <p>Where <code>$color</code> is an hexadecimal value as we can see in my logs
  <a href="https://i.stack.imgur.com/BnX0f.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BnX0f.png" alt="setHex() error" /></a></p>
  <p>But regarding the MapScript <a href="https://mapserver.org/mapscript/php/phpmapscript.html#colorObj" rel="nofollow noreferrer">https://mapserver.org/mapscript/php/phpmapscript.html#colorObj</a> I can use <code>setHex()</code> method.</p>
  <p>It works perfectly fine with <code>$oStyle-&gt;color-&gt;setRGB(255,255,255);</code> for example, so why not <code>setHex()</code>?</p>
  <p>I'm using MapScript 6.4, I have looked at the 6.0.1 release documentation and the <code>setHex()</code> method exists.</p>