This commit modifies the MsgVersion.BtcDecode function to match the
behavior where fields after the first address field (AddrYou) are optional
and only read if the buffer contains remaining bytes.
Unfortunately this means the reader for MsgVersion.BtcDecode must be a
*bytes.Buffer or an error is returned. This is not an issue for the vast
majority of cases since all of the message reading code which is the main
way messages are read is already using a *bytes.Buffer, however, this
change might affect external callers if they are doing something special
with custom readers.
Fixes#14.
This commit changes all cases which generate default timestamps to
time.Now to limit the timestamp to one second precision. The code which
serializes and deserializes timestamps already does this, but it is useful
to make sure defaults don't exceed the precision of the protocol either.
With this change there is less chance that developers using defaults will
end up with structures that have a higher time precision than what will
ultimately be sent across the wire.
