handle the <hosthint> xml tag

[ameidatou]

At the moment <hosthint> xml tag is not handled as part of the parser.
in the nmap dtd the hosthint elements are defined as:

<!-- these elements are written by scan_engine.c:ultrascan_host_pspec_update() -->
<!ELEMENT hosthint (status,address,hostnames)* >

An example of an actual output:

<hosthint><status state="up" reason="arp-response" reason_ttl="0"/>
<address addr="192.168.70.1" addrtype="ipv4"/>
<address addr="00:00:4F:01:10:04" addrtype="mac" vendor="Icann, Iana Department"/>
<hostnames>
</hostnames>
</hosthint>