The previous default policy in netplay for sharing was to always share.
This appears to be causing more confusion than anything else, mainly
because the UI is terrible. The UI is a different problem, but for now,
I've changed the share policy: If you netplay with only one input
configured, it will share; if you netplay with multiple inputs, and
don't explicitly ask to share one, each device will get one client.
Really silly bug had netplay forgetting to unset device availability
when a client goes to spectator mode. As a consequence, in certain
configurations, later joins would automatically choose the wrong device,
and you'd have to manually specify a device to get the right one. This
fixes that.
This abstracts away the details of particular input devices for netplay,
and adds support for mice and (similar) lightguns. Unfortunately, in
practice, no core handles mice or lightguns in a savestate-safe way, so
they need to be used in stateless mode to be reliable, but they do work.
(1) All mode change code unified, so server mode changes and client mode
changes and announcements go through the same functions
(2) New messages which are translateable and work with multiple input
devices
Netplay state demotions, i.e. changes from playing to spectating or
disconnected states, could cause chain disconnections of all other
clients. This was due to a bug in when MODE change messages were sent.
Clients rely on the server sending all messages in its own order, and as
a consequence, the server typically holds messages for retransmission
until they can be retransmitted at the correct time. MODE messages were
not held, so could be sent early. When they were sent early, this caused
other clients to panic and disconnect.
A smaller but much stupider secondary bug was also fixed, in which the
first connection could be dropped due simply to writing connections[0]
instead of connections[i] somewhere.
