Fixing the issue #3292

This change fixes the issue #3292. The details were mentioned in the comments to the issue.
Fixes #3368 value also has to be parsed.
Update DefaultValueValidator.php

Allow the default value to be a closure
Update CHANGELOG.md
Update DefaultValueValidator.php
guide wip [skip ci]
Fixes #3400
Fixed docs on init usage
Application lifecycle and structure schemas
guide wip [skip ci]
Update input-forms.md

is array?
Merge pull request #3404 from djfly/patch-4

Update input-forms.md
Corrected $this->render usage in template engine docs
Redone structure drawing
Fixed drawing misalignment
Added more arrows
Used new drawings in the guide, removed old ones
Improve `exist` validator to support array attributes
Refactoring
Refactoring