newly constructed warehouse inventory popup

[tlongstretch]

When a new warehouse is constructed, it makes sense that it should not show inventory and not be able to change serf/resource in/out state until the building is active (a serf has occupied it). Freeserf checks for active state, but this is the wrong check as the building never becomes 'active'. Instead, suggest using building->has_serf as it has already passed the is_done check.

inside Viewport::handle_special_click

    } else if (building->get_type() == Building::TypeStock) {
          if (!building->is_active()) return 0;

I suggest changing to this, even if isn't true to the original game

    } else if (building->get_type() == Building::TypeStock) {
          if (building->has_serf()){
            // building has holder (Serf::TypeTransporterInventory)
            interface->open_popup(PopupBox::TypeCastleRes);
          }else{
            // holder has not yet arrived, don't draw full detailed inventory
            interface->open_popup(PopupBox::TypeBldStock);
          }

this produces the following popup if a new stock is special-clicked before its sef has arrived