Removed unused Ping Timeout preference

It no longer had any effect. The selective_ping flag is set was ignored by the
server since it now utilizes TCP keepalive.

(cherry-picked from commit b81a702cfa)

data/advanced_preferences.cfg

@@ -56,17 +56,6 @@
     default=yes
 [/advanced_preference]
 
-[advanced_preference]
-    field=ping_timeout
-    name= _ "Ping timeout"
-    description= _ "Number of seconds to wait for a ping reply before timing out. Set to 0 to disable"
-    type=int
-    default=0
-    min=0
-    max=60
-    step=5
-[/advanced_preference]
-
 [advanced_preference]
     field=lobby_auto_open_whisper_windows
     name= _ "Auto-open whisper windows in lobby"

src/game_initialization/multiplayer.cpp

@@ -189,19 +189,6 @@ std::pair<wesnothd_connection_ptr, config> open_connection(std::string host)
 			config& sp = response.add_child("login") ;
 			sp["username"] = login ;
 
-			// Login and enable selective pings -- saves server bandwidth
-			// If ping_timeout has a non-zero value, do not enable
-			// selective pings as this will cause clients to falsely
-			// believe the server has died and disconnect.
-			if(preferences::get_ping_timeout()) {
-				// Pings required so disable selective pings
-				sp["selective_ping"] = false;
-			} else {
-				// Client is bandwidth friendly so allow
-				// server to optimize ping frequency as needed.
-				sp["selective_ping"] = true;
-			}
-
 			sock->send_data(response);
 			sock->wait_and_receive_data(data);
 

src/preferences/game.cpp

@@ -135,8 +135,6 @@ manager::manager() :
 			}
 		}
 	}
-
-	//network::ping_timeout = get_ping_timeout();
 }
 
 manager::~manager()
@@ -403,11 +401,6 @@ void set_network_host(const std::string& host)
 	preferences::set("host", host);
 }
 
-unsigned int get_ping_timeout()
-{
-	return lexical_cast_default<unsigned>(preferences::get("ping_timeout"), 0);
-}
-
 std::string campaign_server()
 {
 	if(!preferences::get("campaign_server").empty()) {

src/preferences/game.hpp

@@ -78,8 +78,6 @@ class acquaintance;
 	std::string network_host();
 	void set_network_host(const std::string& host);
 
-	unsigned int get_ping_timeout();
-
 	std::string campaign_server();
 	void set_campaign_server(const std::string& host);