Send updates only when attributes change about lance HOT 2 CLOSED

Fixed with commit 858fe60

from lance.

As a first implementation, I'm changing the server to send updates
for objects which have changed. i.e. if at least one attribute changed, the object
will be broadcast.

This is not as optimal as suggested, but actually works better on games
which are position-sensitive. By assuming that the entire netscheme is transmitted,
we don't need to flag which attributes are included in the event. And the
object gets tightly packed.

The fix will also send a "complete sync" when a new player has joined.

from lance.