Merge pull request #9 from sforshee/master

Fix build with Linux 5.3

Add support to linux 4.18

linux 4.18 uses a new struct nf_nat_range2 for nf_nat_setup_info.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

Small Changes for 3.7

Since the arrival of IPv6 NAT, the related code has become more generic.
The RTSP module must also follow these changes to compile and run:
 - new "protoff" argument on some functions,
 - new includes because nf_nat_rule.h doesn't exist anymore.

Small Changes for 3.6

Thanks to Benoit Lorand who pointed me to this needed change for kernel
version 3.6.

Small changes for 3.3

Some #defines and a struct got renamed in 3.3 so change them
accordingly.

Convert NIPQUAD to %pI4

NIPQUAD no longer exists so replace it with the %pI4 format extension.

Small changes for 2.6.26

Small changes for 2.6.25

Completely reverted the last changes since they were wrong.

Small API Changes for 2.6.23