colibris: introduce skin variants, in order to customize the rendering

This provide a nice way to change the colors of main containers from settings file. See comment inside settings for how it works

src/node/handler/PadMessageHandler.js

@@ -1065,6 +1065,7 @@ async function handleClientReady(client, message)
     // mile wide...
     var clientVars = {
       "skinName": settings.skinName,
+      "skinVariants": settings.skinVariants,
       "accountPrivs": {
           "maxRevisions": 100
       },

src/node/utils/Settings.js

@@ -62,6 +62,8 @@ exports.faviconTimeslider = "../../" + exports.favicon;
  */
 exports.skinName = null;
 
+exports.skinVariants = "super-light-toolbar super-light-editor light-background";
+
 /**
  * The IP ep-lite should listen to
  */