To that effect, bump liberty and the xC relay protocol version.
Relay events have been reordered to improve forward compatibility.
Also prevent use-after-free when serialization fails.
xP now slightly throttles activity notifications,
and indicates when there are unacknowledged commands.
Rendering takes the current buffer into account,
so change its value before using it, not afterwards.
The order happened to not matter on at least Windows,
because we just queue a message.
