inet_pton() implementation for Windows XP

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
Oskari Timeri added to AUTHORS file

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
Improved error handling in nn_inet_pton()

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>