code: function getAvailableViewTypes(diagramTypeName) {
          var metaClass = _global.meta[diagramTypeName],
              views     = [];
          if (metaClass.super) {
              views = getAvailableViewTypes(metaClass.super);
          }
          if (metaClass.views) {
              var i, len, item;
              for (i = 0, len = metaClass.views.length; i < len; i++) {
                  item = metaClass.views[i];
                  views.push(item);
              }
          }
          return views;
      }
docs: Return all available view types of a diagram type.
  @param {string} diagramTypeName
  @return {Array.<string}>}