Multicast chat messages

Only the sender and the recipients receive the chat messages.
This commit only has an affecto on messages where the addressee(s) are
selected through the dropdown. Addressee(s) selected with a "/" command
are still sent to evevyone and filteret by the receiver.

source/network/scripting/JSInterface_Network.cpp

@@ -41,6 +41,8 @@
 
 #include "third_party/encryption/pkcs5_pbkdf2.h"
 
+#include <optional>
+
 namespace JSI_Network
 {
 u16 GetDefaultPort()
@@ -237,11 +239,25 @@ void KickPlayer(const CStrW& playerName, bool ban)
 	g_NetClient->SendKickPlayerMessage(playerName, ban);
 }
 
-void SendNetworkChat(const CStrW& message)
+void SendNetworkChat(const ScriptRequest& rq, const CStrW& message, JS::HandleValue handle)
 {
 	ENSURE(g_NetClient);
 
-	g_NetClient->SendChatMessage(message);
+	if (handle.isNullOrUndefined())
+	{
+		g_NetClient->SendChatMessage(message, std::nullopt);
+		return;
+	}
+
+	auto receivers = std::make_optional<std::vector<std::string>>();
+	if (!Script::FromJSVal(rq, handle, *receivers))
+	{
+		ScriptException::Raise(rq, "The second argument to `SendNetworkChat` has to be either an Array "
+			"or a nullish value.");
+		return;
+	}
+
+	g_NetClient->SendChatMessage(message, std::move(receivers));
 }
 
 void SendNetworkReady(int message)