Fixes #3179: removed duplicate validation rules from User model in advanced app, removed User::create()

Fix #3265

Merge branch 'stringhelper-truncate' of github.com:Alex-Code/yii2 into Alex-Code-stringhelper-truncate

Conflicts:
	framework/CHANGELOG.md

Adding a new additional validation rule in the gii-crud generator enforcing the expected format.

Fix bootstrap templates

setting writable folders in init-script

[ci skip] overwrite -> override

fixes #3252

fixes #3252

also improved unit tests for querybuilder buildLikeCondition

corrected app dir example and removed license code from example.

[Guide] Fix link

fix typo in the word Semantic

Improved the advanced app template documentation.

Fixes #3268: Fixed the bug that the schema name in a table name was not respected by `yii\db\mysql\Schema`