KQUEUE: new compile-time constant
only resize to result from wait_for_read() if using kqueue

Fixed ticks per second detection for Linux.

set_seed(): range check the seed string

seed the SURF generator
filter ipv6 addrs out of root_hints if !ipv6

dot_sane(): simple dfa to verify the sanity of a dotted name

use cpython.bytes
use libc.errno

expose several socket methods to C/Cython/pxd