Improve `exist` validator to support array attributes
Refactoring
Refactoring
Tests updated
Tests updated
MigrateCommand enhancement. `all` option added for `down` action.
CHANGELOG updated
Comments updated
Tests updated
ExistValidator count logic fix
CHANGELOG
CHANGELOG fixed
`allowArray` introduced.
changed comments #3446
CHANGELOG updated
fixed console errorHandler class
Merge pull request #3447 from lynicidn/patch-1

changed comments #3446
rest guide WIP [skip ci]
ExistValidator refactoring
docs about multiple grids on one page.