pfeil now using sqrt(xm*ym) instead of fm

breaks compatibility for some old figures,
but it is so much an improvement ...

pub/share/wups11a.ps

@@ -1390,7 +1390,8 @@ WuGdict11a begin
    grestore
    } def
 /pfeil { % x[local] y[local] rot siz len[global]
-   fm 5 copy
+   % fm 5 copy % replaced by the following line 10jan13
+   dup xm x ym mul sqrt 5 copy
    pop pfeilspitze
    x pop
    x 4 2 roll % len rot x y