FEAT(client): add starttalking and stoptalking to the socket rpc inte…

…rface

If mumble isn't allowed to listen to all input from an input device, for example when running as wayland client, ptt events can be sent via socket rpc, and, in the case of wayland, the keybinding can be done by the compositor. mumble-voip#3675 implements this for dbus.
To avoid executing the rather large mumble binary to do the rpc, one could also do something like this:
echo '<self><starttalking>starttalking</starttalking></self>' | socat - UNIX-CONNECT:/tmp/MumbleSocket

Implements mumble-voip#1594

src/mumble/SocketRPC.cpp

@@ -163,6 +163,14 @@ void SocketRPCClient::processXml() {
 					g.mw->qaAudioDeaf->trigger();
 				}
 			}
+			iter = qmRequest.find(QLatin1String("starttalking"));
+			if (iter != qmRequest.constEnd()) {
+				g.mw->on_PushToTalk_triggered(true, QVariant());
+			}
+			iter = qmRequest.find(QLatin1String("stoptalking"));
+			if (iter != qmRequest.constEnd()) {
+				g.mw->on_PushToTalk_triggered(false, QVariant());
+			}
 			ack = true;
 		} else if (request.nodeName() == QLatin1String("url")) {
 			if (g.sh && g.sh->isRunning() && g.uiSession) {

src/mumble/main.cpp

@@ -298,6 +298,10 @@ int main(int argc, char **argv) {
 								   "                Undeafen self\n"
 								   "  toggledeaf\n"
 								   "                Toggle self-deafen status\n"
+								   "  starttalking\n"
+								   "                Start talking\n"
+								   "  stoptalking\n"
+								   "                Stop talking\n"
 								   "\n");
 
 				QString helpOutput = helpMessage + rpcHelpBanner + rpcHelpMessage;