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
Summary: Rename test files to use new name
Reviewed By: gkassabli
Differential Revision: D4265235
fbshipit-source-id: 0090d3949828058baf7435f33d4068de92756bad