Vala 0.56.9
===========
 * Various improvements and bug fixes:
  - codegen: Add missing EXTERN flag for GType function of error domains
    [#1449]
  - codegen: Improve handling of sealed classes [#1451]
  - vala: Report an error when trying to chain up to inaccessible private
    ctor [#1445]
  - vala: Fix spaces for attributes when writing property accessors
  - girwriter: Fix c:type attribute for real struct parameters [#1444]
  - testrunner: Add support to check generated header
  - manual: Update from wiki.gnome.org

 * Bindings:
  - gio-2.0: Ease implemention of GLib.ActionGroup [#1447]
  - glib-2.0: Fix return-type of GLib.SourceOnceFunc [#1446]
  - glib-2.0: Add ConvertError.{NO_MEMORY,EMBEDDED_NUL}
  - gtk4: Pick up fix for Gdk.Toplevel.compute_size.size parameter
  - vapi: Add documentation to GLib.Math that '-X -lm' may be needed when
    compiling [#1388]