- allows to have dynamic definition of attributes depended on the
  instance
- there was no real need for it to be static. Places that used it static
  have been refactored.

fixes #1318

issue #1317

far better than depending on fat guzzle

fixes #1319

Model::attributes() has been made static

as suggested in issue #1316

fixes #1316

[ci skip]

"yii\sphinx\ActiveQuery" updated to throw exception on conflict between "asArray" and "snippetByModel" options.