reduce recommended cloak bits from 80 to 64
reduce recommended cloak bits from 80 to 64

From testing on darwin; shaves 3 characters off the cloaked hostname,
and 64 bits of entropy is fine (a collision is expected after 2**32
~= 4 billion distinct CIDRs).

DanielOaks/oragono,oragono/oragono,oragono/oragono,DanielOaks/oragono,oragono/oragono