RBAC: decoupled rules from assignments and items, implemented php manager
removed duplicated joins when using joinWith and via relations

fixes #2650
Merge pull request #2981 from yiisoft/fix-duplicated-joins

removed duplicated joins when using joinWith and via relations
Fixed test break.
fixed test break
Fixes #499: Decoupled `Rule` from RBAC `Item`
Fixed code formattins issues
Removed test entries for MSSQL, Oracle
Removed custom Rule constructor
Splitted saveRule into insertRule and updateRule
Adjusted guide
Merge pull request #2974 from yiisoft/decouple-bizrules-from-auth-items

RBAC: decoupled rules from assignments and items, implemented php manager
Fixed typo
changelog update [skip ci]
Changed tabs to spaces in changelog
Added support to allow an event handler to be inserted at the beginning of the existing event handler list
Improved action filter and action execution flow by supporting installing action filters at controller, module and application levels
Moved all filter classes to namespace `yii\filters`
fixed doc [skip ci]
Fixes #2986.