tcpblast benchmark

1. src/tools/tools/netrate/netblast
2. increase MTU (ifconfig em0 mtu 65536 or so; never tried that myself)
3. ports/benchmarks/tcpblast
4. build something with nc:
server: nc -l 1234 > /dev/null
client: dd if=/dev/zero bs=1m | nc serverIP 1234
which will eliminate disk latency...