port ckey in deadchat from yogs (shiptest-ss13#2187)

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## About The Pull Request
ports yogstation13/Yogstation#4134

## Why It's Good For The Game

helps people find each other

## Changelog

:cl:
add: adds a preference to show your username in deadchat
/:cl:

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---------

Signed-off-by: GenericDM <34109002+GenericDM@users.noreply.github.com>
Co-authored-by: Generic DM <genericdm.dm@gmail.com>

code/__DEFINES/preferences.dm

@@ -41,6 +41,7 @@
 #define CHAT_GHOSTLAWS (1<<11)
 #define CHAT_LOOC (1<<12)
 #define CHAT_LOGIN_LOGOUT (1<<13)
+#define CHAT_GHOSTCKEY (1<<14)
 
 #define TOGGLES_DEFAULT_CHAT (CHAT_OOC|CHAT_DEAD|CHAT_GHOSTEARS|CHAT_GHOSTSIGHT|CHAT_PRAYER|CHAT_RADIO|CHAT_PULLR|CHAT_GHOSTWHISPER|CHAT_GHOSTPDA|CHAT_GHOSTRADIO|CHAT_BANKCARD|CHAT_GHOSTLAWS|CHAT_LOOC|CHAT_LOGIN_LOGOUT)
 

code/modules/client/preferences_toggles.dm

@@ -296,6 +296,17 @@ TOGGLE_CHECKBOX(/datum/verbs/menu/settings, listen_looc)()
 	return C.prefs.chat_toggles & CHAT_LOOC
 //EndWS Edit
 
+TOGGLE_CHECKBOX(/datum/verbs/menu/Settings, chat_ghostckey)()
+	set name = "Show/Hide ckey in deadchat"
+	set category = "Preferences"
+	set desc = "Toggle if players will see your ckey in deadchat"
+	usr.client.prefs.chat_toggles ^= CHAT_GHOSTCKEY
+	usr.client.prefs.save_preferences()
+	to_chat(usr, "Your ckey is [(usr.client.prefs.chat_toggles & CHAT_GHOSTCKEY) ? "now" : "no longer"] visible in deadchat.")
+	SSblackbox.record_feedback("nested tally", "preferences_verb", 1, list("Toggle ckey in Deadchat", "[usr.client.prefs.toggles & CHAT_GHOSTCKEY ? "Enabled" : "Disabled"]")) //If you are copy-pasting this, ensure the 2nd parameter is unique to the new proc!
+/datum/verbs/menu/Settings/chat_ghostckey/Get_checked(client/C)
+	return C.prefs.chat_toggles & CHAT_GHOSTCKEY
+
 TOGGLE_CHECKBOX(/datum/verbs/menu/Settings, listen_bank_card)()
 	set name = "Show/Hide Income Updates"
 	set category = "Preferences"

code/modules/mob/mob_say.dm

@@ -90,7 +90,7 @@
 			alt_name = " (died as [real_name])"
 
 	var/spanned = say_quote(say_emphasis(message))
-	var/source = "<span class='game'><span class='prefix'>DEAD:</span> <span class='name'>[name]</span>[alt_name]"
+	var/source = "<span class='game'><span class='prefix'>DEAD:</span> <span class='name'>[(src.client.prefs.chat_toggles & CHAT_GHOSTCKEY) ? "([src.key]) " : ""][name]</span>[alt_name]"
 	var/rendered = " <span class='message'>[emoji_parse(spanned)]</span></span>"
 	log_talk(message, LOG_SAY, tag="DEAD")
 	if(SEND_SIGNAL(src, COMSIG_MOB_DEADSAY, message) & MOB_DEADSAY_SIGNAL_INTERCEPT)