almost finish tcp send, but not tested yet..
Merge branch 'master' of https://github.com/fengjingchao/peer_server

Conflicts:
	tmp/B.chunks
move others to etc
clear ack_cnt explicitly
finish tcp sending and some tests
recored dups even for obsolete acks
add last packet sent
add last packet sent
dup number is 3, plus normal ack, total should be 4
dup number is 3, plus normal ack, total should be 4
Merge branch 'master' of github.com:yifan-gu/peer_server
fix restransmit
fix restransmit
retransmit
retransmit
fix ssthreshold
change sendto to spiffy_sendto
Merge pull request #5 from yifan-gu/master

almost finishing the sending part, more tests are needed..