the client matches the objects in a snapshot against the ones it already
has by global id, and anything it cannot find it builds from scratch.
our next id was the highest one in play plus one, recomputed at every
spawn - so as soon as a unit died its id came free and the next spawn
took it. at five snapshots a second the client was destroying and
rebuilding models faster than they could appear, which is why units
fought and shot while invisible.
the counter is per battle now and only ever goes up, starting past the
towers.
cc92831d06