Use xfce4-terminal for saturnin-iam command(s)

dotfiles/saturnin/dmenu.ini

     iam:GONE        = saturnin iam gone
     iam:BACK        = saturnin iam back
     iam:UNDOCKING   = saturnin iam undocking
-    iam:ZLEEPING    = urxvt -title 'iam:ZLEEPING' -e saturnin iam zleeping
+    iam:ZLEEPING    = xfce4-terminal -T 'iam:ZLEEPING' -e 'saturnin iam zleeping'
     kb:us           = setxkbmap us
     kb:cz           = setxkbmap cz