Turn off the General Index for release notes.

General Index is pretty useless for release notes, so get rid of it.
It just contained random links to random release notes.
Handle a bunch of renamed methods.

This change uses the six.moves pseudo-module for xrange->range,
izip_longest->zip_longest, and raw_input->input.

Testing done: Ran unit tests.

Reviewed at https://reviews.reviewboard.org/r/4937/