Added a debug toolbar panel for MongoDB
merge with upstream
Dynamic naming added to `DbPanel`
`MongoDbPanel` addition mentioned at CHANGELOG.md and README.md
`DbPanel` summary view fixed
Doc links fix
correcting word
Removed unnecessary token generation. We already have it.
Merge pull request #5449 from faxriddin/master

[skip ci] correcting word
updated formatter docs and allow using DateTimeImmutable

see http://derickrethans.nl/immutable-datetime.html
by @derickr
Fixed `yii\mongodb\ActiveRecord` unable to fetch 'hasMany' referred by array of `\MongoId`
Merge branch 'master' of github.com:yiisoft/yii2
translation_to_uzbek
Update README.md
typo fix

close #5455
typo fix

close #5454
guide improvement about default values
fix code style php5.4 syntax

close 5458
tranlation_to_uzbek
Merge pull request #5460 from faxriddin/master

[skip ci] translated part of *-upgrade-*.md