Add scrollable chat log to in-game chat (enter hotkey)

[rdxi]

page up to scroll up page down to scroll down escape to go to bottom

[historic_bruno]

We had this before via the console, but that's probably not the best place for it, since all the formatting / player colors were lost. I think it's a little higher priority though.

[historic_bruno]

It should be logged to a file as well.

[sanderd17]

If the chat message is a command, it could be saved in the GuiInterface and be gathered or filtered on request.

Note that only raw, user-submitted strings should be treated as commands. Chats coming from the AI or other parts of the GUI will be re-send on replays, and may also contain translations (so could cause OOS).

Logging to a file is automatic by having it in commands.txt (the raw command) and in saved games (by serializing the GuiInterface).

Being able to analyse the chats in the commands.txt would also help with determining when a certain problem occured.

[Imarok]

dupe of #4069 (closing this one, because #4096 has a wip patch already)

[elexis]

Replying to sanderd17:

Chat shouldn't be done as a simulation system, as it means

• while the game is paused or lagging, one can't chat
• observers can't and shouldn't send simulation commands
• Chat isn't used anywhere in the simulation

But I agree that it would be convenient to have them in the commands.txt for replays. So perhaps one can forward the chat messsages of the most recent turn to the replay logger, so that it writes a simulation command that is equivalent to a regular networked chat message.

Should there be a way for people to share replays without sharing the chat, i.e writing a commands.txt and a commands_chat.txt? Or should we rather write one file with a custom format for the chat in the first place? It could also contain evens like disconnects, rejoins, kicks and pausing.