Removed double quotes

Added Traditional Chinese translations

Removed Sphinx installation from foreign PPA

https://getcomposer.org/doc/03-cli.md#require

Fixes #3957: Added more straightforward configurable properties to `BlameableBehavior`, `SluggableBehavior` and `TimestampBehavior`

Fixes #4409: Upper case letters in subdirectory prefixes of controller IDs were not properly handled

Add References Badge to Readme

check with Object::canSetProperty()

fixes #4305, close #4211

how did that manage to pass before...?

Array attribute relations

* master:
  Update output-data-widgets.md
  Fixes #4370: fileinfo extension is required for FileValidator.
  Fixes #4342
  Fixes #3887
  minor refactoring of FileValidator.
  Doc translate for rest-resources
  Better fix for Dropdown container options
  #4388: CORS filter fixes:
  Fixed test break.
  #4310: Removed `$data` from signature of `yii\rbac\ManagerInterface`
  Update .travis.yml
  Update ActiveRecordInterface.php
  Fixes #4384.
  Sphinx distributed indexes support provided
  typo fix [skip ci]
  Fixes #3611: Refactored query caching.