Kill kwapply.

Closes #433.
Fix versionadded in docs to 0.10.0 release
Merge pull request #550 from theanalyst/doc-version-fix

Fix versionadded in docs to 0.10.0 release
Properly add yield-from, using python's real "yield from".

The yield-from that existed previously wasn't actually implementing the
full complexity of "yield from":

  http://legacy.python.org/dev/peps/pep-0380/#formal-semantics

... this includes passing along errors, and many other things.

It may be that we could/should implement the full algorithm of yield
from and backport it to pre-python 3.3 though.
Restore backport of yield-from macro to Python 2.7, with documented caveats
Switched the conditional yield-from defmacro to be (if-not (or PY33 PY34))

This makes things consistently the inverse of the logic of whether to
define the AST version.
Note about limitations of yield-from's macro edition
Remove the yield-from backport macro.

It turns out the "conditional building of the macro" wasn't, and it was
just using the macro regardless.

Thus, there is no longer yield-from on pre-python-3.3 systems.

Updated docs and tests to reflect this as well.
Removing superfluous blank line with whitespace.