fixed Markdown::process() to make it compatible with parent declaration.

fixes #1606

no need to download codeception via composer when phar is used.
fixes #1913

[SK] Added translation.

* '1818-gii-excess-forms' of https://github.com/johonunu/yii2:
  using camelcase
  changed vars
  Gii excess forms. Fixes #1818

Added sticky futter. Fixes #1822

* '1907-sr-language' of https://github.com/johonunu/yii2:
  rearanged language array
  remove sr-cyrl, it's the same as sr
  Serbian translation. Fixes #1907

Conflicts:
	framework/messages/config.php

Fix phpdoc generation in gii model generator.

[IMPORTANT] Path corrections

zh-cn add