Enable the ImageMagick filter documented upstream.  This provides
loaders for common formats which XImaging does not handle internally.

Index: src/XImaging.ad
--- src/XImaging.ad.orig
+++ src/XImaging.ad
@@ -26,6 +26,10 @@ XImaging*tileSizeList: 80,120,160
 XImaging*tileAspectRatio: 4:3
 
 
+!! Additional formats handled by the ImageMagick runtime dependency.
+XImaging.filter.imagemagick: convert %n pam:-
+XImaging.filter.imagemagick.suffixes: gif psd svg xcf
+
 !! Uncomment to customize viewer and browser view background colors
 ! XImagingViewer*view.background: darkgray
 ! XImagingViewer*view.backgroundPixmap: wide_weave
