uvloop 0.9.1

on Python PyPI

Stop using malloc for uv_request* handlers.

Fix loop.add_reader(), loop.add_writer(), loop.remove_reader(),
and loop.remove_writer() to better track socket objects.

Fix loop.sock_recv(), loop.sock_sendall(), loop.sock_recv_into(),
and loop.sock_connect() to correctly handle Task.cancel().

Better handle immediate cancellation of loop.create_connection().

Make unit tests stricter: ensure loop.call_exception_handler()
does not get called, unless it's expected.