助手类，clone于yii2 framework，版本：2.0.17。
包含：
-
ArrayHelper
-
FileHelper
-
Html
-
HtmlPurifier
-
Inflector
-
Json
-
Markdown
-
Security
-
StringHelper
-
VarDumper
参考文档：
https://www.yiiframework.com/doc/api/2.0/yii-helpers-arrayhelper
https://www.yiiframework.com/doc/api/2.0/yii-helpers-filehelper
https://www.yiiframework.com/doc/api/2.0/yii-helpers-html
https://www.yiiframework.com/doc/api/2.0/yii-helpers-htmlpurifier
https://www.yiiframework.com/doc/api/2.0/yii-helpers-inflector
https://www.yiiframework.com/doc/api/2.0/yii-helpers-markdown
https://www.yiiframework.com/doc/api/2.0/yii-base-security
https://www.yiiframework.com/doc/api/2.0/yii-helpers-stringhelper
https://www.yiiframework.com/doc/api/2.0/yii-helpers-vardumper
Yii2原注释保留。LICENSE.md为Yii2自带的BSD协议。
部分方法是Yii2独有，做了修改或者删除。