Rough creation of a doc style guide

Should have started this before; important to maintain consistency.
HHVM compatibility Fixes for Yii 2 Console Application
Fix for comparing numeric attributes in JavaScript
Better Gii caption english
Merge pull request #3367 from MethyleneGaming/master

HHVM compatibility Fixes for Yii 2 Console Application
Fix for comparing numeric attributes in JavaScript
Merge remote-tracking branch 'origin/master'

Conflicts:
	framework/assets/yii.validation.js
Merge pull request #3368 from technixp/master

Fix for comparing numeric attributes in JavaScript
[NL] brought translations up to date
[NL] Removed app.php
Merge pull request #3373 from Blizzke/master

[NL] brought translations up to date
Fixes #2913: RBAC `DbManager` is now initialized via migration
`BaseActiveRecord::findAll()` comment fix
Merge pull request #3375 from creocoder/baseactiverecord-findall-comment-fix

`BaseActiveRecord::findAll()` comment fix
#2435 Tests for integrity exception
Merge pull request #3370 from kartik-v/patch-2

[ci skip] Better English for Gii Caption
`@inheritdoc` from interfaces and params
Merge branch 'master' of github.com:yiisoft/yii2

* 'master' of github.com:yiisoft/yii2: (43 commits)
  `BaseActiveRecord::findAll()` comment fix
  Fixes #2913: RBAC `DbManager` is now initialized via migration
  [NL] Removed app.php
  [NL] brought translations up to date
  Fix for comparing numeric attributes in JavaScript
  Better Gii caption english
  Fix for comparing numeric attributes in JavaScript
  HHVM compatibility Fixes for Yii 2 Console Application
  Rough creation of a doc style guide
  typo
  Finished Edits
  Edited up to Active Record
  renamed chapter to section [skip ci]
  Catalan translation
  Edited up through "I18N"
  Cleaned Up
  updated guide toc [skip ci]
  Update concept-behaviors.md
  Fixed wrong links [skip ci]
  Fixed document for multisort in BaseArrayHelper
  ...
Implemented throwing \yii\db\IntegrityException on DB integrity errors
Fixes #2435: `yii\db\IntegrityException` is now thrown on database integrity errors instead of general `yii\db\Exception`