Complex sentence: There was also an official extension library, "zii", which was eventually merged with the core framework; it has been bundled in every release since Yii version 1.1.0, and includes additional behaviors and widgets, such as grids and jQuery UI.
Split into simpler sentences: There was also an official extension library, "zii", which was then merged with the core framework. It is bundled in every release since Yii version 1.1.0, and it includes additional behaviors and widgets, such as grids and jQuery UI.