Add support for hidden fields
Added new config entry network.dhcp_filter_by_message_types
Expand  network.dhcp_filter_by_message_types to an array
New method make_pcap_filter
Use make_pcap_filter to create the filter
Updated NEWS files
Fix typo
Merge pull request #260 from jrouzierinverse/feature/pfdhcplistener-alt-filters

More precisly define which dhcp message types we are listening for