v3.1

Bug #4634: Unify math library

Bug #4674: cocos2d-x github repository is huge (and slow)

Bug #4771: Move _physicsWorld from Scene to Layer.

Bug #4782: LGPL contamination suspicion

Bug #4906: Label created with system font is still visible when its opacity is 0

Bug #4990: cocos2d-console maybe raise error when build android on windows with release mode.

Bug #4999: Label:Text is unsharp if it's created by smaller font.

Bug #5020: Windows Phone Orientation

Bug #5032: A potential crash bug of Lua binding

Bug #5054: Label:Text have black border if it's created with system font on WP8/WINRT.

Bug #5099: Optimization for Value

Bug #5121: UILoadingBar init render flicker

Bug #5141: Memory leak in ParticleSystem

Bug #5188: fix a crash when doing monkey test on cpp-tests package

Bug #5252: Label:It could be possible that for using outline cause crash.

Bug #5277: Label:It could be possible that for using outline and invoking 'Director::setContentScaleFactor' cause label show nothing.

Feature #4692: LiquidFun sample

Feature #4727: Support run the sample projects in engine with console.

Feature #4783: add a outline shader to shader sprite

Feature #4859: Add a widget to play video

Feature #4861: UI system support focus

Feature #4865: Check out if can use system widget to play video

Feature #4867: Use system widget to play video on Android

Feature #4868: Use system widget to play video on iOS

Feature #4869: Add more control options of playing video on Android

Feature #4870: Add a ui widget of playing video

Feature #4992: Add test case to play video

Refactor #5055: Cleanup UI framework code

Refactor #5056: Pull the UI tests from ExtensionTest to the outside

Refactor #5057: Use c++11 best practice and unify some apis in UI module

Refactor #5110: Cleanup obscure function name

Refactor #5118: Remove WidgetType enum in Widget class

Refactor #5160: Dispatch a custom event after an animation frame is displayed

Docs #4678: Analyze memory usage