Merge pull request #4123: Fix iInFlightTCPPings check

This PR contains 2 parts:

According to the documentation of Settings::IMaxInFlightTCPPings, a
value of 0 should disable the check. That was not the case though which
is corrected by this commit.

We have received reports about users getting disconnects even though
their network was fine (#3448). By increasing this limit by default, we
should be able to circumvent that.

src/mumble/ServerHandler.cpp

@@ -504,7 +504,7 @@ void ServerHandler::sendPingInternal() {
 		return;
 	}
 
-	if (g.s.iMaxInFlightTCPPings >= 0 && iInFlightTCPPings >= g.s.iMaxInFlightTCPPings) {
+	if (g.s.iMaxInFlightTCPPings > 0 && iInFlightTCPPings >= g.s.iMaxInFlightTCPPings) {
 		serverConnectionClosed(QAbstractSocket::UnknownSocketError, tr("Server is not responding to TCP pings"));
 		return;
 	}

src/mumble/Settings.cpp

@@ -408,7 +408,7 @@ Settings::Settings() {
 	bAutoConnect = false;
 	ptProxyType = NoProxy;
 	usProxyPort = 0;
-	iMaxInFlightTCPPings = 2;
+	iMaxInFlightTCPPings = 4;
 	bUdpForceTcpAddr = true;
 	iPingIntervalMsec = 5000;
 	iConnectionTimeoutDurationMsec = 30000;