[Bug Fix] Fix #guild rename, #killallnpcs, and #worldwide message errors. (#1904)

- #guild rename was checking argument count and not allowing you to rename guilds to names that had spaces.
- #killallnpcs was crashing zones when used sometimes due to getting a nullptr somewhere in the loop.
- #worldwide message was using just the first word of the message sent using the command, not all of them.

zone/gm_commands/worldwide.cpp

@@ -62,7 +62,7 @@ void command_worldwide(Client *c, const Seperator *sep)
 	}
 	else if (sub_command == "message") {
 		if (sep->arg[2]) {
-			std::string message = sep->arg[2];
+			std::string message = sep->argplus[2];
 			quest_manager.WorldWideMessage(
 				Chat::White,
 				fmt::format(