Update yii.php
Italian Translation Typo Fix
Update Language Translation
Fixed italian translation
Add Chinese translation

Signed-off-by: qiansen1386 <qiansen1386@gmail.com>
polish the Translation
Continue to polish chinese Translation. Fix all the issue mentioned by @samdark. Removed all comments.

Signed-off-by: qiansen1386 <qiansen1386@gmail.com>
Polish Chinese translation. Symbols

Signed-off-by: qiansen1386 <qiansen1386@gmail.com>
Correction of chinese core message translation.

Signed-off-by: qiansen1386 <qiansen1386@gmail.com>
Update yii.php
Added translations for danish language
Merge pull request #1871 from Theill11/danish-translation

Added translations for danish language
added polish translation
Merge branch 'master' into polish-translation

Conflicts:
	framework/yii/messages/config.php
fix languages list in messages config
Merge pull request #1873 from nineinchnick/polish-translation

Added polish translation
Type fix
Updared extensions guide to include info about PSR-4 autoloading
Merge pull request #1877 from plusodinminus/patch-2

Type fix
Updated extension guide to suggest stricter naming of packages