Information packet (#382)

This PR adds an "I" packet which returns the server information. This
can be used by external programs and the launcher to get information
about a server without having to connect it to. It can be toggled in the
config and in lua.

src/TNetwork.cpp

@@ -20,6 +20,7 @@
 #include "Client.h"
 #include "Common.h"
 #include "LuaAPI.h"
+#include "THeartbeatThread.h"
 #include "TLuaEngine.h"
 #include "TScopedTimer.h"
 #include "nlohmann/json.hpp"
@@ -256,6 +257,9 @@ void TNetwork::Identify(TConnection&& RawConnection) {
             boost::system::error_code ec;
             write(RawConnection.Socket, buffer("P"), ec);
             return;
+        } else if (Code == 'I') {
+            boost::system::error_code ec;
+            write(RawConnection.Socket, buffer(Application::Settings.getAsBool(Settings::Key::General_InformationPacket) ? THeartbeatThread::lastCall : ""), ec);
         } else {
             beammp_errorf("Invalid code got in Identify: '{}'", Code);
         }