message: Cache common subexpression connectorDirection in checkTubeConnection
diff: @@ -46,19 +46,20 @@ bool checkTubeConnection(Tile& tile, Direction dir, ConnectorDir sourceConnector
  }
  Structure* structure = tile.structure();
  + const auto connectorDirection = structure->connectorDirection();
  if (sourceConnectorDir == ConnectorDir::CONNECTOR_INTERSECTION)
  {
  if (dir == Direction::East || dir == Direction::West)
  {
  - if (structure->connectorDirection() == ConnectorDir::CONNECTOR_INTERSECTION || structure->connectorDirection() == ConnectorDir::CONNECTOR_RIGHT || structure->connectorDirection() == ConnectorDir::CONNECTOR_VERTICAL)
  + if (connectorDirection == ConnectorDir::CONNECTOR_INTERSECTION || connectorDirection == ConnectorDir::CONNECTOR_RIGHT || connectorDirection == ConnectorDir::CONNECTOR_VERTICAL)
  {
  return true;
  }
  }
  else // NORTH/SOUTH
  {
  - if (structure->connectorDirection() == ConnectorDir::CONNECTOR_INTERSECTION || structure->connectorDirection() == ConnectorDir::CONNECTOR_LEFT || structure->connectorDirection() == ConnectorDir::CONNECTOR_VERTICAL)
  + if (connectorDirection == ConnectorDir::CONNECTOR_INTERSECTION || connectorDirection == ConnectorDir::CONNECTOR_LEFT || connectorDirection == ConnectorDir::CONNECTOR_VERTICAL)
  {
  return true;
  }
  @@ -66,14 +67,14 @@ bool checkTubeConnection(Tile& tile, Direction dir, ConnectorDir sourceConnector
  }
  else if (sourceConnectorDir == ConnectorDir::CONNECTOR_RIGHT && (dir == Direction::East || dir == Direction::West))
  {
  - if (structure->connectorDirection() == ConnectorDir::CONNECTOR_INTERSECTION || structure->connectorDirection() == ConnectorDir::CONNECTOR_RIGHT || structure->connectorDirection() == ConnectorDir::CONNECTOR_VERTICAL)
  + if (connectorDirection == ConnectorDir::CONNECTOR_INTERSECTION || connectorDirection == ConnectorDir::CONNECTOR_RIGHT || connectorDirection == ConnectorDir::CONNECTOR_VERTICAL)
  {
  return true;
  }
  }
  else if (sourceConnectorDir == ConnectorDir::CONNECTOR_LEFT && (dir == Direction::North || dir == Direction::South))
  {
  - if (structure->connectorDirection() == ConnectorDir::CONNECTOR_INTERSECTION || structure->connectorDirection() == ConnectorDir::CONNECTOR_LEFT || structure->connectorDirection() == ConnectorDir::CONNECTOR_VERTICAL)
  + if (connectorDirection == ConnectorDir::CONNECTOR_INTERSECTION || connectorDirection == ConnectorDir::CONNECTOR_LEFT || connectorDirection == ConnectorDir::CONNECTOR_VERTICAL)
  {
  return true;
  }
  