1.6.2: README tweaks

1.6.1: tiny README/description fix+fiddling

1.6.0: use markcoroutinefunction if available

1.5.0: type hints / static type checking

1.4.8: __init__: fix composed function flattening

* Fixes a corner case bug when a wrapper object of a
  composed function is composed. In those situations:
  * `isinstance(function, composed)` could be true;
  * `function` is the wrapper instead of being the
    composed function instance;
  * `function.__wrapped__` is the composed function
    instance instead of being the innermost function.
* Performance-wise, this fix performs better on well
  optimizing Python implementations (PyPy, Cython)
  than alternatives which peform negligibly better on
  barely-optimizing Python implementations (CPython),
  and is at worst negligibly worse than the pre-fix
  version.

This reverts commit a10c194.

1.4.7: make __init__ error messages more Pythonic

* I can't remember where I saw precedent for quoting the class name.
* Built-in functions like `int` and `float` use the `foo()` style.
* Con: no longer unambiguous no matter what __name__ is set to.
* Pro: errors now communicate in a more conventional, familiar way.

1.4.6: README example fixes and doctest testing

Fix setup.py for edge-cases no one uses

Version 1.4.4

Fix bound composed methods' attributes on Python 2

* Python 3 switched to the new attribute names.
* Python 2.5 and below had only the old names.
* So Python 2 code might be written to use the
  old names and never even try the new names.