Change `AboutDialog::set_website_label` to take `Option`
Change `AboutDialog::set_website_label` to take `Option`

EPashkin/rust-gnome-gtk,gkoz/gtk-rs-gtk,rust-gnome/gtk,daa84/gtk,gkoz/gtk-rs-gtk,Susurrus/gtk,Susurrus/gtk,EPashkin/rust-gnome-gtk,gkoz/rust-gnome-gtk,daa84/gtk,gkoz/rust-gnome-gtk,rust-gnome/gtk