Questionable external links on qt.io

There are numerous external links on qt-project.org that are not needed for the proper operation of the site, some of them controversial with respect to privacy.

As example, the main qt-project.org/doc/ refers externally to fonts.google.com, google-analytics.com, google.com/jsapi*, gravatar.com and addthis.com.

Unneeded dependencies should be removed. If user tracking is considered absolutely necessary from a technical point of view (hard to imagine a reason for that, but not precluding the possibility) it should be done locally, not by third parties.