When translation is missing source language should be used for formatting

This reverts commit c94131b8.

fixed configs

check error level in error handler

Update error.md

typo fix

Fixes #2054: Added support for using custom application configuration with the console command runner

need to confirm the exception properties in Yii 2

Feature/toolbar ui 2

Fixes #2341, fixes #2317: moved codeception dependecies to "suggest" section, fixed codeception version on stable branch

issue yiisoft/yii2-coding-standards#4