This code is taken from Massimo's comment in #1786 and MR !834. It doesn't fix
a crash as this was already handled in !404, yet the missing prompt after
hitting "clear" was clearly not consistent with how one expect a clear feature
to work.
At least now, we've got a prompt back immediately after clearing.
Just add a no-op flush() as I think it's actually unneeded in the context of a
GtkTextView GUI. At least it doesn't cause issues with copy-pasted code or when
using external libraries using the sys.stdout.flush() interface.
I may have missed things. That is the problem of non-compiled script
languages. There is also a known warning:
> DeprecationWarning: Gtk.Dialog.set_alternative_button_order_from_array is deprecated
I'll see later about this one.
Push-time note: calling various functions is actually broken right now
in the console since the late API changes (it was working fine yesterday
evening when I tested the same python-console code). Pushing anyway for
now.
