Fix getPosition() bug

At present, calling `getPosition()` on a node returns a reference to the node's private `_position` variable. This can lead to mysterious bugs in seemingly simple code. Consider this:

	var pos = node.getPosition();
	pos.x += 5; // bad! this modifies the node's position

This pull request fixes the bug.
Merge pull request #1734 from VisualSJ/develop-3.0

Issue #4608: Minimize the size of engine core
Merge pull request #1746 from NatWeiss/patch-7

Fix getPosition() bug
Merge pull request #1747 from VisualSJ/develop-3.0

Closed #4728: window._p cannot be modified in some cases
fix compatibility and performance for ctor
fix bug
if-> if else
Fixed #4731: cc.CardinalSplineAt function renamed to cc.cardinalSplineAt
Fixed #4731: Renamed cc.CardinalSplineAt in CCDrawNode
Refactor #4722: Uppercase functions to lowercase
Merge branch 'develop-3.0' of git://github.com/cocos2d/cocos2d-html5 into develop-3.0

Conflicts:
	cocos2d/core/CCDrawingPrimitives.js
	cocos2d/core/platform/CCMacro.js
Merge pull request #1749 from VisualSJ/develop-3.0

Issue #4608: Fixed a bug - build.xml compile error
Refactor #4722: Apply all Uppercase functions to lowercase in CCMacro
Merge branch 'develop-3.0' of git://github.com/cocos2d/cocos2d-html5 into develop-3.0
Fixed #4720: Fix a small bug for cc.randomMinus1To1
Merge pull request #1750 from pandamicro/develop-3.0

Fixed #4722: Rename all Uppercase functions to lowercase in CCMacro
Merge pull request #1751 from VisualSJ/develop-3.0

Issue #4608: Fixed a bug that BinaryLoader.js is missing in the moduleCo...
Merge pull request #1748 from joshuastray/develop-3.0

fix compatibility and performance for ctor
Merge pull request #1752 from VisualSJ/develop-3.0

Issue #4608: Fixed a bug that BinaryLoader.js is missing in the build.xm...