Don't immediately run links added to an Event/AsyncResult while it is running callbacks. Fixes #771.

Make the forewarn about 2.6 a permanant part of the readme that ends up on PyPi. It's not necessary to change whatsnew_1_1 in this branch, as RTD deploys from master. [skip ci]

Issue some warnings for patch_all with invalid parameters

Update socket docs to clarify their duplication of stdlib interface; tone down the warnings. [skip ci]

See changelog.rst for details.

Also skip the 'make' step on Windows if installing from an sdist (piggyback the Unix method of looking for Makefile/Makefile.ext). Ref #757.

Notes about cython on windows. XXX: Duplicated a couple places, intro.rst and README.rst, we should refactor.

- Kill older builds for the same PR automatically.
- Separate building and running tests.
  This lets us build and install a wheel up front so we don't have to do
  it again after running the tests (to distribute). This shaves 1+
  minute off each build for faster overall feedback.

Ignore the BlockingIOError name in server.py if running pyflakes on Py2; also sort the error lines by filename so they're easier to find. [skip ci]