[4o6]add support for DHCPv6 relay
[4o6] add check for U flag in dhcpv6 transid field
[4o6] fixed pkt4o6->pk6 unpack to avoid twice pkt6 unpack() in dhcp6_srv
add pkt4o6 class unit test--still in progress
add pkt4o6 class unit test --complete
[4o6]add BaseIPC class unit test --complete
[4o6]delete some no use words
[4o6]delete some no use declaration
[4o6]insert <sys/types.h> <sys/socket.h>,which is need by AF_UNIX and socket
[4o6]add dhcp4o6_ipc class unit test --complete
using theirs
[4o6]insert two needed headers
[4o6]create CreatePkt4o6_case1() function
[4o6]improve two tests functions, it works.
[4o6]update retract style.
Merge pull request #4 from asdassZY/4o6

[4o6] add exceptions for BaseIPC
[406] improved exceptions ipc.h
Merge pull request #5 from wyqbupt/4o6

[4o6] basic test caces for BaseIPC, DHCP4o6IPC and pkt4o6
[4o6] add exception handler when constructing DHCP4o6IPC in dhcp4 server
[4o6] add exception handler when constructing DHCP4o6IPC in dhcp6 server