Move configuration to new YGConfig and pass them down to CalculateLayout

Summary:
Move configuration to new ```YGConfig``` and pass them down to CalculateLayout. See #418 .

Adds ```YGConfigNew()``` + ```YGConfigFree```, and changed ```YGSetExperimentalFeatureEnabled``` to use the config.

New function for calculation is ```YGNodeCalculateLayoutWithConfig```.
Closes https://github.com/facebook/yoga/pull/432

Reviewed By: astreet

Differential Revision: D4611359

Pulled By: emilsjolander

fbshipit-source-id: a1332f0e1b21cec02129dd021ee57408449e10b0

javascript/sources/global.hh

@@ -9,7 +9,4 @@
 
 #pragma once
 
-void setExperimentalFeatureEnabled(int feature, bool enabled);
-bool isExperimentalFeatureEnabled(int feature);
-
 unsigned getInstanceCount(void);