Merge pull request #1043 from linshun/iss2580_v2.1.5

Merged v2.1.5 to master branch
Fixed #2441 avoid using temp cc.p for cc.Follow
Fixed #2441 avoid using temp cc.p for cc.CardinalSplineTo/cc.CardinalSplineBy
Fixed #2441 avoid using temp cc.p for cc.Grid3DAction
Fixed #2441 avoid using temp cc.p for cc.ActionInterval
Fixed #2441 avoid using temp cc.p for cc.PageTurn3D
Fixed #2441 avoid using temp cc.p for cc.TiledGrid3DAction
Issue #2445 refactor code for rendering classes
Issue #2441 reduce read accumulatedDiff times in cc.CardinalSplineTo update
Issue #2441 add local pointer to reduce read  times
fixed #2445 refactor code for Performance
Merge branch 'develop' of Cocos2d-html5 into Iss2445_RewriteCtor

Conflicts:
	cocos2d/base_nodes/CCNode.js
	cocos2d/label_nodes/CCLabelTTF.js
	cocos2d/sprite_nodes/CCSpriteFrame.js
fixed #2459: fix Accelerometer bug on UCWeb version 9.0 and below.
fixed #2445 refactor code for rendering classes to optimize performance
Fixed #2445 correct a mistake in CCScheduler.js when refactoring code for performance
Merge pull request #1044 from xingsenma/cc.p,cc.size

Fixed #2441: Improve update function of Action, avoid using temp cc.p or cc.size
Merge pull request #1047 from dingpinglv/Iss2445_RewriteCtor

Fixed #2445 refactor code for rendering classes to optimize performance
Merge pull request #1048 from ShengxiangChen/issue2459_accelerometerBug

fixed #2459: fix Accelerometer bug on UCWeb version 9.0 and below.
fixed #2468 Fixed a bug of CCBReader that ControlButton doesn't work when controller is _jsControlled
fixed a bug that engine can't load from single engine file