Stop the futile process of trying to enumerate which kinds of exceptions distutils may throw (the latest potential addition: ValueError). Closes #1115.
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.
This avoids the complexity of ensuring that cython is installed at build time.
This function has changed recently and it makes more sense to stop maintaining a separate copy, even though it does introduce our first required dependency.
This optimization is currently activated only if Cython is present when Tornado is installed.
This should let pypi pick it up automatically on upload.