[BUNDLE] Allow different diff output

[Szilveszter Farkas]

> It seems unlikely to me that diff_cmd_helper helper is actually what you
> want in a GUI.  As the name says, it's a helper for the diff command,
> and is very commandline-oriented.  I'd suggest using show_diff_trees or
> compare_trees instead.

i get the point, i'll use those functions instead. sorry for the noise :)

regards,
szilveszter / phanatic