tweak to $() so that it brands its single-shot iterable;

fixing bug with $() io do-routine helper improperly detecting and passing-through iterables like strings/arrays/etc

various metaprogramming improvements

IO.doEither internal refactor, adding yield* delegation tests for IO and State

adding some tests for IO.do/IO.doEither

adding link to todoovy codepen demo

fixing missing dependency in State

major breaking changes:

Update README.md

README: tweaking description of IO

adding link to ebook format

MONADS guide: fixing a few mistakes in code snippets

MONADS guide: various improvements for clarity and consistency

io/iox: adding applicative 'ap()', including docs and tests

io/iox: adding missing very-long concat.pipe() tests