* Use childrenMap directly to prevent creating an NSArray in ASDK for ASLayoutSpec children
* Add locking for parent property in ASLayoutSpec
* Remove unnecessary import
* Add newline
* Add NSFastEnumeration to ASEnvironment and ASDisplayNode / ASLayoutSpec
* Change NSMutableArray initializer to arrayWithCapacity:
* Move ASLayoutSpec+Private.h into Private folder
Fixes building with Swift
* Remove lock for ASLayoutSpec parent