Update about dialog design to not use a swarm of dialogs
Update about dialog design to not use a swarm of dialogs

This is a modernization of the GtkAboutDialog look done
by William Jon McCann. The most noteworthy changes are:
- no more subdialogs
- show license short text in the main dialog
- less verbose email link formatting
- the dialog is modal to its transient parent

Adamovskiy/gtk,simokivimaki/gtk,grubersjoe/adwaita,ebassi/gtk,alexlarsson/gtk,msteinert/gtk,simokivimaki/gtk,Adamovskiy/gtk,bratsche/gtk-,Lyude/gtk-,chergert/gtk,Adamovskiy/gtk,jigpu/gtk,Distrotech/gtk2,Adamovskiy/gtk,ahodesuka/gtk,davidgumberg/gtk,davidgumberg/gtk,jigpu/gtk,simokivimaki/gtk,ebassi/gtk,jadahl/gtk,alexlarsson/gtk,ahodesuka/gtk,ebassi/gtk,simokivimaki/gtk,davidgumberg/gtk,bratsche/gtk-,jadahl/gtk,davidgumberg/gtk,alexlarsson/gtk,davidt/gtk,jessevdk/gtk,davidt/gtk,jessevdk/gtk,bratsche/gtk-,alexlarsson/gtk,Sidnioulz/SandboxGtk,jadahl/gtk,Adamovskiy/gtk,simokivimaki/gtk,jigpu/gtk,msteinert/gtk,Lyude/gtk-,chergert/gtk,Lyude/gtk-,Lyude/gtk-,alexlarsson/gtk,ahodesuka/gtk,Adamovskiy/gtk,alexlarsson/gtk,ahodesuka/gtk,simokivimaki/gtk,jigpu/gtk,jadahl/gtk,Lyude/gtk-,grubersjoe/adwaita,grubersjoe/adwaita,davidt/gtk,jadahl/gtk,Adamovskiy/gtk,alexlarsson/gtk,Distrotech/gtk2,Lyude/gtk-,Distrotech/gtk2,Lyude/gtk-,bratsche/gtk-,davidt/gtk,Distrotech/gtk2,jessevdk/gtk,ahodesuka/gtk,chergert/gtk,jessevdk/gtk,ahodesuka/gtk,ahodesuka/gtk,ebassi/gtk,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,davidgumberg/gtk,Sidnioulz/SandboxGtk,jessevdk/gtk,jessevdk/gtk,ebassi/gtk,Adamovskiy/gtk,jigpu/gtk,jadahl/gtk,jadahl/gtk,grubersjoe/adwaita,chergert/gtk,Lyude/gtk-,Distrotech/gtk2,msteinert/gtk,msteinert/gtk,davidgumberg/gtk,msteinert/gtk,ebassi/gtk,grubersjoe/adwaita,jigpu/gtk,chergert/gtk,chergert/gtk,ahodesuka/gtk,davidgumberg/gtk,Sidnioulz/SandboxGtk,chergert/gtk,Sidnioulz/SandboxGtk,bratsche/gtk-,davidt/gtk,Distrotech/gtk2,Sidnioulz/SandboxGtk,alexlarsson/gtk,davidgumberg/gtk,jigpu/gtk,bratsche/gtk-,msteinert/gtk,davidt/gtk,jessevdk/gtk,Sidnioulz/SandboxGtk,jadahl/gtk,chergert/gtk,jigpu/gtk