Add a proper interface for IGameConnection

Previously the IGameConnection interface was empty, but the code which used the
module actually did a dynamic_cast down to the GameConnection implementing
class and used its methods directly, thereby breaking the module abstraction.

Now, the methods used by the UI code have been added as pure virtuals in the
IGameConnection interface, eliminating the need for the dynamic downcast.

include/igameconnection.h

@@ -6,7 +6,14 @@
 class IGameConnection : public RegisterableModule
 {
 public:
-    //TODO: to be determined...
+    virtual void setCameraSyncEnabled(bool enable) = 0;
+    virtual void backSyncCamera() = 0;
+    virtual void reloadMap() = 0;
+    virtual void setAutoReloadMapEnabled(bool enable) = 0;
+    virtual void setUpdateMapLevel(bool on, bool always) = 0;
+    virtual void doUpdateMap() = 0;
+    virtual void togglePauseGame() = 0;
+    virtual void respawnSelectedEntities() = 0;
 };
 
 const char* const MODULE_GAMECONNECTION = "GameConnection";

radiant/gameconnection/GameConnection.cpp

@@ -24,9 +24,11 @@ static std::string messagePreamble(std::string type) {
 static std::string actionPreamble(std::string type) {
     return messagePreamble("action") + fmt::format("action \"{}\"\n", type);
 }
+#if 0
 static std::string queryPreamble(std::string type) {
     return messagePreamble("query") + fmt::format("query \"{}\"\n", type);
 }
+#endif
 
 
 int GameConnection::newSeqno() {
@@ -62,7 +64,7 @@ void GameConnection::think() {
             //validate and remove preamble
             int responseSeqno, lineLen;
             int ret = sscanf(_response.data(), "response %d\n%n", &responseSeqno, &lineLen);
-            assert(ret == 1); ret;
+            assert(ret == 1);
             assert(responseSeqno == _seqnoInProgress);
             _response.erase(_response.begin(), _response.begin() + lineLen);
             //mark request as "no longer in progress"
@@ -72,8 +74,7 @@ void GameConnection::think() {
     }
     else {
         //doing nothing now: send async command if present
-        bool sentAsync = sendAnyPendingAsync();
-        sentAsync = false;  //unused
+        sendAnyPendingAsync();
     }
     _connection->think();
     if (!_connection->isAlive()) {

radiant/ui/UserInterfaceModule.cpp

@@ -162,7 +162,7 @@ void UserInterfaceModule::registerUICommands()
 
     // FIXME: should not dynamic_cast, required methods should be in the
     // IGameConnection interface
-	if (GameConnection *gameconn = dynamic_cast<GameConnection*>(GlobalGameConnection())) {
+	if (IGameConnection *gameconn = GlobalGameConnection()) {
 		GlobalCommandSystem().addCommand("GameConnectionCameraSyncEnable",
 			[gameconn](const cmd::ArgumentList&) { gameconn->setCameraSyncEnabled(true); });
 		GlobalCommandSystem().addCommand("GameConnectionCameraSyncDisable",