xtaci/kcptun v20161031

Even more optimizations on memory

on GitHub

1. xmitBuf is shared among sess.go/fec.go/kcp.go.
2. cacheline optimized fecgroup.

$ go version
go version go1.7.3 darwin/amd64
xtaci/smux@9d1cf79
xtaci/kcp-go@0721a11
c601a18

MD5 (kcptun-linux-amd64-20161031.tar.gz) = 3838ee8ced9281415323f7e84212dd86
MD5 (kcptun-linux-386-20161031.tar.gz) = a0c7b66d0c395fe78aa7d0702fdfbd1d
MD5 (kcptun-darwin-amd64-20161031.tar.gz) = a79b9657d864f024e54cac567f0e73d3
MD5 (kcptun-darwin-386-20161031.tar.gz) = 2f11177301ea4eaed59cfae0baf06472
MD5 (kcptun-windows-amd64-20161031.tar.gz) = 035f813cca823a01419d01c132bb3560
MD5 (kcptun-windows-386-20161031.tar.gz) = be8124204676808305a905037f0fc750
MD5 (kcptun-freebsd-amd64-20161031.tar.gz) = b273e873ddbc93a70abc5d768ceb11c7
MD5 (kcptun-freebsd-386-20161031.tar.gz) = 9f9aa85cd681762ba03e0118fc4500b4
MD5 (kcptun-linux-arm-20161031.tar.gz) = 20eea11bcfefb0fa45beeead19e467f1