fixes #1161

Proposal for #31: email component based on SwiftMailer

Proposal for accessing populated relations

[ci skip]

Method 'yii\mail\MailerInterface::compose()' reworked allowing rendering message body.

Modified application templates so when trying to log in when already logged in it just redirects to homepage instead of throwing exceptions

Refactored View

* 'master' of github.com:yiisoft/yii2:
  Fix typo

related to #1151

Fixed typo

* 'master' of github.com:yiisoft/yii2:
  Fixes #1146: Gii generates wrong relation.

fixes #1146

- 'body()' renamed to 'renderBody()'
- new 'body()' method introduced