3.95.1: (unstable) Distro packagers should probably not package this yet. * Prepare for gtkmm-4.0. Require giomm-2.62 and gtkmm-4.0. Require C++17 (Kjell Ahlstedt) * Remove the "Plugs and Sockets" chapter and example (Kjell Ahlstedt) * Update most chapters and example programs. (Kjell Ahlstedt, Murray Cumming) * Add "Changes in gtkmm 4" chapter (incomplete) (Kjell Ahlstedt) * Headers and Linking section: Replace broken link (Kjell Ahlstedt) Bug #777879 (Ramana Venkata) * Use auto instead of explicit types where appropriate. Adapt to Glib::RefPtr as std::shared_ptr. (Murray Cumming) * Adapt to enums in classes. (Murray Cumming, Kjell Ahlsedt) Bug #86864