Finalize 3.2 release notes
Set version number to 3.2.
Update README.rst to match docs/index.rst.
Bump version number to 3.3.dev1
Refactor the unwieldy tox.ini file.

Fill in some gaps in the coverage (mostly on the python 3 side, and
using more consistent dependencies throughout) and move the 3.x tests
that don't care about a specific 3.x version to 3.3.

This is still less thorough than the travis.yml, which runs everything for
every python version.
Fix msvc compile error and improve 64 bit compatibility
Merge pull request #973 from cgohlke/patch-1

Fix msvc compile error and improve 64 bit compatibility
Add a new TORNADO_EXTENSION environment variable for testing purposes.

This variable can be set to 0 to suppress or 1 to require the use of the
extension (instead of the default to use it when it is available but silently
fall back).  Require the extension to be present on travis-ci.
Add better debugging for ImportErrors resulting from TORNADO_EXTENSION=1
Reinstate the 'cd maint' in .travis.yml.

This turned out to be breaking the speedups module.
Don't require the extension to be present when building docs.
Merge branch 'branch3.2'
Require the extension to be built in tox -full runs.
Add pycares to the -full tox configs and remove custom resolver tests.

The resolvers are tested in netutil_test when their dependencies are
available, and re-running the entire test suite with a different resolver
is unlikely to expose any new problems.  (the resolver tests are still
present in travis.yml for now, though)
Allow and encourage the use of file objects instead of integer fds in IOLoop.

This fixes a problem in tests in which a closing IOLoop would os.close()
all of its file descriptors while socket objects for those fds still
existed.  When those socket objects were garbage collected, they would
close the fd a second time (by which time it may have been reassigned
to a new socket).

Due to subtleties of garbage collection this has only been observed
with the asyncio event loop in tests of curl_httpclient.
Document file descriptor change and start new release notes.
Pass the correct file object to IOLoop handler functions.
Make tornado.netutil.add_accept_handler pass a fileobj to the IOLoop.

Officially allow mixing of fds and file objects so that callers of
add_accept_handler don't need to know about this change.

As a side effect, fixes a problem with autoreload on windows.

Closes #737.
Fix a typo that snuck into the autoreload docs.
Remove some vestigial references to 2to3.