[ci skip]

fixes #4012

yii\redis\ActiveRecord::deleteAll() refactoring - no need to write to socket 2 times when nothing found

yii\redis\ActiveRecord::deleteAll() refactoring - no need to write to socket 2 times when nothing found

Fixes #2955: Changed the signature of ActiveQuery constructors and `ActiveRecord::createQuery()` to simplify customizing ActiveQuery classes

so information about changed values is available in `afterSave`-event.

fixes #2892

allow extending only one class to add scopes, fixes #2146

TODO:

- [ ] adjust guide docs
- [ ] adjust README files of extensions
- [ ] finish work and fix test breaks

issue #1313

Moved file and path related methods from StringHelper to FileHelper, renamed StringHelper byte methods not to be misused as string methods

- 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

- make use of traits
- short array
- better implementation of query findByPk