code: function(category, filter) {
              var r = [];
              for (var i in this.registered_node_types) {
                  var type = this.registered_node_types[i];
                  if (filter && type.filter && type.filter != filter) {
                      continue;
                  }
  
                  if (category == "") {
                      if (type.category == null) {
                          r.push(type);
                      }
                  } else if (type.category == category) {
                      r.push(type);
                  }
              }
  
              return r;
          }
docs: Returns a list of node types matching one category
  @method getNodeType
  @param {String} category category name
  @return {Array} array with all the node classes