* upstream: (35 commits)
Fixes#1691: added “viewport” meta tag to layout views.
Fixed the issue that query cache returns the same data for the same SQL but different query methods
moved section
subsection added
typo [skip ci]
docs about response
Fixes#1586: `QueryBuilder::buildLikeCondition()` will now escape special characters and use percentage characters by default
docs improved
csrf docs added
Fixes#1685: UrlManager::showScriptName should be set true for tests.
Fixes#1688: ActiveForm is creating duplicated messages in error summary
change back the visibility of findTableNames to protected.
Typo fix.
Fixes#1681: Added support for automatically adjusting the "for" attribute of label generated by `ActiveField::label()`
Simplified tests.
Fixes#1631: Charset is now explicitly set to UTF-8 when serving JSON
Fixed typo
added html layout for mail component in basic app
CS fixes.
Merge branch 'debug_module_improvements' of github.com:Ragazzo/yii2 into Ragazzo-debug_module_improvements
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