Add SettingsEngine option to disable Active TCP

Use SettingsEngine.DisableActiveTCP(true)

settingengine.go

@@ -86,6 +86,7 @@ type SettingEngine struct {
 	iceTCPMux                                 ice.TCPMux
 	iceUDPMux                                 ice.UDPMux
 	iceProxyDialer                            proxy.Dialer
+	iceDisableActiveTCP                       bool
 	disableMediaEngineCopy                    bool
 	srtpProtectionProfiles                    []dtls.SRTPProtectionProfile
 	receiveMTU                                uint
@@ -348,6 +349,11 @@ func (e *SettingEngine) SetICEProxyDialer(d proxy.Dialer) {
 	e.iceProxyDialer = d
 }
 
+// DisableActiveTCP disables using active TCP for ICE. Active TCP is enabled by default
+func (e *SettingEngine) DisableActiveTCP(isDisabled bool) {
+	e.iceDisableActiveTCP = isDisabled
+}
+
 // DisableMediaEngineCopy stops the MediaEngine from being copied. This allows a user to modify
 // the MediaEngine after the PeerConnection has been constructed. This is useful if you wish to
 // modify codecs after signaling. Make sure not to share MediaEngines between PeerConnections.