Add filter support to PCAP socket
Add IPv6-only support for the listener
Fix a crash if address to bind is NULL
Filter only received packets on PCAP (no error handling for now)
Add cdata_get_remote to retrieve sockaddr_storage from remote peer
implement sock_send_data_to - similar to sendto
cdata_set_remote implementation
Add built-in SHA1 code.
Edit Makefile to link in sha1 code.