Instead of having just one `|split` message, we should have multiple.

[scheibo]

Maybe instead of having just one |split message, we can have multiple.

|split|p1, etc. That'd probably be easier to read/etc than literally six repetitions of the same message.

Originally posted by @Zarel in https://github.com/Zarel/Pokemon-Showdown/pull/5317#issuecomment-474154108

The idea is that

|split|p1
SECRET
PUBLIC

would mean the same thing as

|split
PUBLIC
SECRET
PUBLIC
SECRET

and

|split|p2
SECRET
PUBLIC

would mean the same thing as

|split
PUBLIC
PUBLIC
SECRET
SECRET

Originally posted by @Zarel in https://github.com/Zarel/Pokemon-Showdown/pull/5317#issuecomment-474678889

I think this protocol change is important in a world with @MacChaeger's 4 player battles to allow for not sharing information between teammates (or an opponent in a free-for-all!) Because this changes protocol, I believe the change needs to first be made on the client (to handle the new protocol as well as the old one), after which point the server can be updated

[Zarel]

This change doesn't affect client, which only receives sanitized messages. It only affects the sim protocol – i.e. the protocol the sim process and the main process use to communicate with each other.

[scheibo]

Ah! Quite right, I forgot that the server handles this. I was thinking maybe replays have splits in them, but thats clearly wrong as theyre from the spectators POV. It seems its mainly battle.ts/battle-stream.ts/server/sockets.js and maybe a few other places that need updating.