Removed file system folder for migration tests. Using XCode groups only.
PlugInNode gets mainBundle injected to enable testing.
PlugInNodes tests added.
Refactoring:
Modern syntax for arrays and dictionaries.
Using constants for pasteboard types.
Simplified if statement.
More strict types used.
Logging of dealloc disabled for testing.
Refactoring:
Extracted some methods.
Renamed some paramaters to be more verbose than a single character.
Used each syntax to remove if testing of array coung > 0.
Overridden properties loop iterating backwards as preparation for bugfix.
Bugfix for #897. Sprite 9 Slice crashing Sprite Builder.