src: improve default text output

src: improve default text output

This patch improves default plain text output by mimicing the
default output of libnl-nft.

While at it, several %lu has been translated to use %"PRIu64"
for correctness.

[ I have added the policy to string translation --pablo ]

Signed-off-by: Giuseppe Longo <giuseppelng@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>