Yii HTML 3.6

Yii HTML 3.6 版本包发布了。有一些提升和修复：

• Throw InvalidArgumentException in Html::renderAttribute() when attribute name is empty or contains forbidden symbols.
• Add Stringable and array values support to textarea tag.
• Add backed enumeration value support to CheckboxList and RadioList widgets.
• Fix output of null value attributes in Html::renderTagAttributes() .