Allow specifying `uselang` with `Page.revisions()` and
`Site.usercontributions()` to get localized parsed comments with
`prop=parsedcomment`.

Breaking change: Change the `Site.ask()` method to produce less nested
output. Basically, change `yield {title: answer}` to `yield answer`. The
title is included in the answer object after all.

The rvexpandtemplates parameter has been removed, but we can use
action=expandtemplates instead.

This fixes tests not being added to the source package.