RFC 7232 Compliance for yii\filters\HttpCache

[skip-ci] Update structure-widgets.md

changed bootstrap namespace to jui

exclude parts that have different default values

fixes test break in HHVM due to export of a closure

Translated rest-rate-limiting.md and rest-error-handling into Russian [skip ci]

Fixes #4697: MSSQL query builder does not work for newer MSSQL versions when LIMIT is used without ORDER BY

Dynamic model typo fix

[ci skip] Fixing typo in guide-structure-modules

added source map generation so that styling can be debugged easily.