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.

fixed broken code block

4342 mssql driver updates

Doc translate for rest-resources

Better fix for Dropdown container options

Better fix for #3443 that does not break BC and allows widget to be extensible.

- Upgrade the documentation to match filter code
- Fix bad default behavior with Access-Control-Allow-Credentials
- Fix missing "s" in header Access-Control-Request-Method / Access-Control-Allow-Methods

temporarily skip app tests as they seem to be broken somehow

fixes #3026