Dropping qtwebkit

Hi, Qtwebkit has been unmaintained for a long time (last release from annulen's fork was almost 3 years ago) and is plagued with security issues by now. Most consumers are either dead upstream, of they use it to provide optional functionality that can be disabled at build time. I propose to drop it from our repos, together with all packages which use it non-optionally. Other distros such as Opensuse and Gentoo have done it already. If there are no objections, I will open a todo list to disable the dependency in all packages where it's possible, and otherwise drop them.