fixed missing delimiter in capabilities string when using stealth mode

src/blackcore/network_vatlib.cpp

@@ -61,6 +61,7 @@ namespace BlackCore
             capabilities += "=1";
             if (m_loginMode == LoginStealth)
             {
+                capabilities += ":";
                 capabilities += "STEALTH"; // TODO  m_net->capability_Stealth
                 capabilities += "=1";
             }