message: add removeElement method
diff: @@ -252,11 +252,14 @@ export class PanelModelBase extends Base implements IConditionRunner {
  this.addPanel(panel);
  return panel;
  }
  - public removeQuestion(question: QuestionBase) {
  - var index = this.elements.indexOf(question);
  + public removeElement(element: IElement) {
  + var index = this.elements.indexOf(element);
  if (index < 0) return;
  this.elements.splice(index, 1);
  }
  + public removeQuestion(question: QuestionBase) {
  + this.removeElement(question);
  + }
  public runCondition(values: HashTable<any>) {
  if (!this.visibleIf) return;
  if (!this.conditionRunner) this.conditionRunner = new ConditionRunner(this.visibleIf);
  