title: How to use custom theme in iccube reporting v6?
body: <p>In iccube reporting V5x, I was able to load a custom theme by adding the following instruction in <code>ic3report-config.js</code></p>
  
  <pre><code>ic3RegisterTheme('Pkcs', 'theme/', 'PkcsTheme.js' , 'PkcsTheme.css' );
  </code></pre>
  
  <p>then inside <code>pkcstheme.js</code>,  I used </p>
  
  <pre><code>var ic3;
  (function(a) {
      a.Themes.registerTheme({
          name: "PKCS",
          cssCls: "pkcs-theme",
          boxHeaderCls: "pkcs-header",
          reportContainerDefaultStyle: "pkcs",
          amChartsDefaultStyle: "Pkcs Main",
  etc...
  </code></pre>
  
  <p>But, in V6, <code>a.Themes.registerTheme</code> does not exist...</p>
  
  <p>What is the proper way to do this now ?</p>