[Uk][Guide] intro-yii.md [skip ci]
Advanced app `User` model code style fixes
Advanced app `User` model code style fixes
Merge pull request #4117 from creocoder/apps-advanced-common-user-code-style-fixes

[skip-ci] Advanced app `User` model code style fixes
Review requirements

fileinfo is not a hard dependency.
make fileinfo optional requirement
add concept-behaviors.md
Allow single items to set their encoding option
Allow an item to choose if it's encoded.
add concept-components.md
Update concept-components.md
Update CHANGELOG.md
Update CHANGELOG.md
Fixes #4114: Added Security::generateRandomHexKey(), used it for various tokens and default key generation
guide WIP [skip ci]
translated docs (structure-widgets.md) to russian
Merge branch 'master' of git://github.com/yiisoft/yii2 into translation-ru-structure-widgets
Merge pull request #4115 from yiisoft/security-adjustments

Added Security::generateRandomHexKey(), used it for various tokens and default key generation
Merge pull request #4129 from slash686/translation-ru-structure-widgets

[skip ci] Translation of docs to russian (structure-widgets section)
Fixed changelog