Merge pull request #4 from duthils/master

set hard udp buffer size for macosx
reduce timeout detection for active link and establishing p2p connection
relax a bit the timeout, and keep printf for future debug
ok, relax it a bit more
merge UDT v4.11
use micro-second, not CPU Frequence

The cpu frequence is scalable, which creates problems
I broke the Makefile when I merged the latest version of udt4,
now I bring it back !