No more RXRecursiveEnumerator.

It wasn’t copyable, and it was poorly implemented.
Correct a static analysis false positive.
L3TestDefine is wrapped rather conveniently for this purpose.
Don’t duplicate definitions in documentation comments.
This does not silence a static analyzer false positive, but I’m doing it anyway.
All enumerations must conform to NSCopying.
Newlines at ends of files.
Merge pull request #23 from robrix/all-enumerations-must-be-copyable

All enumerations must be copyable