added vim temp files to gitignore
added network structs for packet_info's parsing functions

in order to parse and handle higher-level network structures than the
link-level frame, the following structures were added:
struct private_in6_addr
struct private_ip6_hdr
struct ip
typedef	uint32_t tcp_seq
struct tcphdr
struct tcp_seg
struct ip4_dgram
struct ip6_dgram