With this commit if tsdecrypt detects that the stream is still
encrypted after passing it through decryption it doesn't output it.

You can enable the output of encrypted streams using --output-enc-pass
option.

Using it prevents running of several notification scripts in parallel
which can lead to races if the scripts are used for logging.

This patch adds support for connecting to CAMD over IPv6. Nice addition
is that now tsdecrypt tries each of the addresses returned when CAMD
hostname is resolved and connects to the one that works. Resolving
of the server address is done before each connect, which allows for
uninterupted migration of CAMD servers by just changing their DNS
record.

IPv6 functionality can be disabled by using -4/--ipv4 options or
if you fancy only IPv6 servers -6/--ipv6 can be used.

The limitation is that resolving the hostname is performed only
once at tsdecrypt startup. If DNS changes while tsdecrypt is running,
tsdecrypt won't notice that.

By using this option output can be disabled if there is no currently
received code word.

no-output-filter better describes what the parameter does.
Also fix man page description. output-filter still works but
it is undocumented and kept only for backwards compatability.

I should remember to add options in README.

This workaround is no longer needed because camd socket is now set
TCP_NODELAY and this fixes OSCAM communication.

- Mention man page
- Better examples using long options

Add support for SECA/Mediaguard, Viaccess, Videoguard/NDS, Nagra
and DRE-Crypt.