couple of resource leaks fixes (#2526)

src/input/device_manager.cpp

@@ -490,6 +490,7 @@ bool DeviceManager::load()
     if(input->getName()!="input")
     {
         Log::warn("DeviceManager", "Invalid input.xml file - no input node.");
+        delete input;
         return false;
     }
 
@@ -500,6 +501,7 @@ bool DeviceManager::load()
         GUIEngine::showMessage(_("Please re-configure your key bindings."));
         GUIEngine::showMessage(_("Your input config file is not compatible "
                                  "with this version of STK."));
+        delete input;
         return false;
     }
 

src/network/servers_manager.cpp

@@ -191,6 +191,8 @@ Online::XMLRequest* ServersManager::getLANRefreshRequest() const
                     m_success = true;
                 }   // if received_data
             }    // while still waiting
+
+            delete broadcast;
             if (!m_success)
                 m_info = _("No LAN server detected");
         }   // operation

src/tracks/navmesh.cpp

@@ -46,6 +46,7 @@ NavMesh::NavMesh(const std::string &filename)
     if(xml->getName()!="navmesh")
     {
         Log::error("NavMesh", "NavMesh is invalid. \n");
+        delete xml;	
         return;
     }