Use https instead of http where possible

[kjcole]

I'm setting up a new web site from scratch and following the latest recommendations for content security policies (CSP). As I move documentation generated by Sphinx, I'm finding all sorts of places where "http://" is used when "https://" is available.

While it's true that some of the changes would need to happen upstream, e.g. the jQuery stuff,

• _sphinx_javascript_frameworks_compat.js and doctools.js belong directly to Sphinx
• even though it's only a namespace, not a true URL, http://www.w3.org/2000/svg redirects to https://www.w3.org/2000/svg when entered into a browser, and thus seems like a harmless and very quick & easy change.