iptables_converter.py now python3 ready, all prints changed

No more an exception for unreadable file, simply msg and exit 1
python3 does not complain any longer
distutils replaced by setuptools for -doc package
documentation adapted to version 0.9
Makefile more replaced by cat, README adapted to v0.9
control now shows two packages: iptables-converter and -docs

Dependancies extended about python3
rules rewritten to use overrides_dh_xyz
rules dh_install completely oldfashioned with cd, cp
Version released 0.9

two packages are shipped now:
iptables-converter contains manpage and binary
iptables-converter-doc, this contains the sphinx documentation