Updated AR classes with the latest changes from master to go on with
separation of AR query classes in traits.

Conflicts:
	framework/yii/db/ActiveQuery.php
	framework/yii/db/ActiveRecord.php
	framework/yii/db/ActiveRelation.php

also removed superflous minimum-stability definition

- added example code for application components
- added missing short description

[ci skip]

Little helpful description for Session::cookieParam

allows opening email for view in mail program directly

Code style

Update main.php

Fixed phpDocs [skip ci]

More precise descripton fo Session::cookieParam

FIX: Relation names not mangled in ActiveQuery::normalizeRelation

This reverts commit 7d6d01b4.

Added FileMailer implementation of mailer interface