gtk-demo: Don't use mad mime type guessing
gtk-demo: Don't use mad mime type guessing

... for displaying resources. Instead use the proven and way more
reliable method of trial and error.

It's less code and more portable for a start.
But most of all it displays PNM files as text if you fail to compile
the gdk-pixbuf loader for it.

davidgumberg/gtk,grubersjoe/adwaita,grubersjoe/adwaita,davidgumberg/gtk,ahodesuka/gtk,jadahl/gtk,alexlarsson/gtk,jigpu/gtk,chergert/gtk,Adamovskiy/gtk,jadahl/gtk,grubersjoe/adwaita,Adamovskiy/gtk,ahodesuka/gtk,jadahl/gtk,Lyude/gtk-,jigpu/gtk,ahodesuka/gtk,davidgumberg/gtk,grubersjoe/adwaita,chergert/gtk,chergert/gtk,jessevdk/gtk,Adamovskiy/gtk,Lyude/gtk-,alexlarsson/gtk,ahodesuka/gtk,alexlarsson/gtk,jadahl/gtk,ahodesuka/gtk,chergert/gtk,chergert/gtk,grubersjoe/adwaita,ahodesuka/gtk,jigpu/gtk,ahodesuka/gtk,Lyude/gtk-,jigpu/gtk,jessevdk/gtk,Lyude/gtk-,alexlarsson/gtk,ahodesuka/gtk,Adamovskiy/gtk,jessevdk/gtk,jigpu/gtk,grubersjoe/adwaita,jessevdk/gtk,davidgumberg/gtk,chergert/gtk,jadahl/gtk,jigpu/gtk,alexlarsson/gtk,davidgumberg/gtk,alexlarsson/gtk,alexlarsson/gtk,jigpu/gtk,jessevdk/gtk,chergert/gtk,davidgumberg/gtk,Adamovskiy/gtk,davidgumberg/gtk,Lyude/gtk-,jessevdk/gtk,jadahl/gtk,Lyude/gtk-,davidgumberg/gtk,Adamovskiy/gtk,Adamovskiy/gtk,Adamovskiy/gtk,chergert/gtk,jessevdk/gtk,Lyude/gtk-,jigpu/gtk,Lyude/gtk-,grubersjoe/adwaita,alexlarsson/gtk,jadahl/gtk,grubersjoe/adwaita,jadahl/gtk