Fixes #3568: When the primary query sets `asArray`, it is not respected by the `via` relational query

Fixes #3638: `yii\filters\HttpCache` does not work as expected when session is started before the filter

attempt to fix multiple header issue

fixes #2859

fixes #2988

fixes #3583

fixes #3559

fixes #3893

* consistent-after-save:
  use an AfterSaveEvent class to be consistent
  fixed test break and wrong parameter
  changed updateAttributes to be more simple update
  Ensure consistent behavior in ActiveRecord::afterSave()

Conflicts:
	framework/UPGRADE.md

fixes #3899

fixes #4053

fixes #3324

fixes #4045

issue #746

Translation review intro yii.md

issue #746

issue #746

fixes #4042

fixes #4047

issue #613