3.97.1: (unstable)
Distro packagers should probably not package this yet.

Apart from the changes listed below there are lots of small changes.
Most changes are caused by changes in gtkmm-4.0.
All example programs are compatible with gtkmm 3.97.1.
docs/tutorial/C/index-in.docbook is not fully updated.

* Use glibmm-2.64 instead of glibmm-2.62
  Require gtkmm-4.0 >= 3.97.1
  (Kjell Ahlstedt)
* meson.build: "ninja test" builds the example programs
  README files: meson is the recommended build system
  (Kjell Ahlstedt)
* Builder, example and description: Update use of get_widget() and
  get_widget_derived(). Describe combination with Glib::Property
  (Kjell Ahlstedt)
* Application example: Use Gio::Application::add_option_group()
  (Kjell Ahlstedt) Issue glibmm#46 (Patrick Storz)
* Meson build: Replace shell scripts with Python scripts
  Makefile.am: Distribute files needed when building with Meson
  (Kjell Ahlstedt)
* Builder: Using derived widgets: Update for glibmm
  (Daniel Boles) Merge request !5
* Drop pointless/confusing class around RadioButtons
  (Daniel Boles) Merge request !6
* Don't recommend `new` for an in-class member
  (Daniel Boles) Merge request !7
* Replace Glib::Exception by Glib::Error
  (Kjell Ahlstedt) Issue glibmm#23
* index-in.docbook: Change git.gnome.org to gitlab.gnome.org
  (Kjell Ahlstedt)
* Add examples/book/treeview/custom_treemodel
  (Kjell Ahlstedt) Issue #9 (Danny van Elsen)
* Use Gtk::PopoverMenu and Gtk::PopoverMenuBar instead of the removed
  Gtk::Menu and Gtk::MenuBar.
  Update drag-and-drop examples: Use Gtk::DragSource and DropTarget.
  Examples with toolbars: Replace removed Toolbar and *ToolButton
  by Box and *Button.
  (Kjell Ahlstedt)