- Enh #3562: Adding rotateByCopy to yii\log\FileTarget (pawzar)
- Enh #3574: Add integrity check support for SQLite (zeeke)
- Enh #3597: Nested array support for HTML5 custom "data-*" attributes (armab)
- Enh #3643: Improved Mime-Type detection by using the `mime.types` file from apache http project to dected mime types by file extension (cebe, pavel-voronin, trejder)
- Enh: Added support for using sub-queries when building a DB query with `IN` condition (qiangxue)
- Enh: Supported adding a new response formatter without the need to reconfigure existing formatters (qiangxue)
- Enh: Added `yii\web\UrlManager::addRules()` to simplify adding new URL rules (qiangxue)
