Use a messagebox to display the error when -server is provided without providing a rpc password

(plus part of 7cfbe1fee4)

src/bitcoinrpc.cpp

@@ -2174,7 +2174,7 @@ void ThreadRPCServer2(void* parg)
             strWhatAmI = strprintf(_("To use the %s option"), "\"-server\"");
         else if (mapArgs.count("-daemon"))
             strWhatAmI = strprintf(_("To use the %s option"), "\"-daemon\"");
-        PrintConsole(
+        ThreadSafeMessageBox(strprintf(
             _("Error: %s, you must set a rpcpassword in the configuration file:\n %s\n"
               "It is recommended you use the following random password:\n"
               "rpcuser=bitcoinrpc\n"
@@ -2183,7 +2183,8 @@ void ThreadRPCServer2(void* parg)
               "If the file does not exist, create it with owner-readable-only file permissions.\n"),
                 strWhatAmI.c_str(),
                 GetConfigFile().c_str(),
-                EncodeBase58(&rand_pwd[0],&rand_pwd[0]+32).c_str());
+                EncodeBase58(&rand_pwd[0],&rand_pwd[0]+32).c_str()),
+            _("Error"), wxOK | wxMODAL);
 #ifndef QT_GUI
         CreateThread(Shutdown, NULL);
 #endif