makepanda: Fixes to pview.desktop

It accepts multiple files (not URLs), and it doesn't actually handle startup notification properly, so don't keep showing that spinner

makepanda/pview.desktop

@@ -3,8 +3,8 @@ Name=Panda3D Model Viewer
 GenericName=Model Viewer
 Comment=View Panda3D model files
 TryExec=pview
-Exec=pview %U
-StartupNotify=true
+Exec=pview %F
+StartupNotify=false
 NoDisplay=true
 Terminal=true
 Type=Application