* Simplify applying layout transition in preparation for bigger layout transition API work
* Change from apply to complete in if layout transitions are involved and _applyLayout: to _setCalculatedLayout: for layout
* Change to applySubnodeInsertions and applySubnodeRemovals
* Change from completeTransition to commitTransition and flip logic around when to trampoline to the main thread for implicit hierarchy management
* More internal API improvements
* Fix merge conflicts
* Rename _layout to _calculatedLayout