A new call named ip_pkt is added to manage IP packet.
IP packets are queued by sequence number in tcp_session.
some file names are changed.
type of uint{num}_t replaces the standard type.
ip samples have been checked for corrupted tcp sessions.

a mysterious phenomenon has been found. If ip packet with
zero-length tcp playload were not been removed, then more
tcp session's samples would be detected as corrupted.
class poller which is a wrap of epoll is added.
The problem of failed to capture part outgoing traffic annoys me so much.
timer is added.
The problem of failed to capture part outgoing traffic annoys me so much.
fix calc_tcp_checksum introduced bug.
Merge branch 'tmp_test_tcp_checksum' into dev

Conflicts:
	ip_pkt.cpp
	ip_pkt.h
	postoffice.cpp
	session_manager.h
	thetimer.cpp
pls give me luck.
and the const class member funcion qualifier.
Merge branch 'tmp' into dev
send has been replaced by sendto. it works now.
hard typing work.
get_seq_number's been removed. use get_seq.
just save my work in case of uppredicated events.
god bless.
i'm so tired.