implement tunnels

src/ui/GameWorldView.cpp

@@ -481,7 +481,9 @@ void GameWorldView::placeAtTile(QPoint tile)
             }
         }
     }
-    else if (type == BuildingType::Splitter)
+    else if (type == BuildingType::Splitter
+             || type == BuildingType::TunnelEntry
+             || type == BuildingType::TunnelExit)
     {
         if (!m_sim->buildings().isTileOccupied(tile))
         {

src/ui/SelectedBuildingPanel.cpp

@@ -59,7 +59,8 @@ bool isProductionBuilding(BuildingType type)
 
 bool isBeltLike(BuildingType type)
 {
-    return type == BuildingType::Belt || type == BuildingType::Splitter;
+    return type == BuildingType::Belt || type == BuildingType::Splitter
+        || type == BuildingType::TunnelEntry || type == BuildingType::TunnelExit;
 }
 
 QString rotationLabel(Rotation r)

src/ui/VisualsLoader.cpp

@@ -124,6 +124,8 @@ const BuildingEntry kBuildingEntries[] = {
     { "salvage_bay",       BuildingType::SalvageBay        },
     { "belt",              BuildingType::Belt              },
     { "splitter",          BuildingType::Splitter          },
+    { "tunnel_entry",      BuildingType::TunnelEntry       },
+    { "tunnel_exit",       BuildingType::TunnelExit        },
 };
 
 }  // namespace