Method add_and_follow

plugins/spectate.cpp:197–210

    }

    void add_and_follow(color_ostream &out, df::unit *unit) {
        // if we're currently following a unit, add it to the history if it's not already there
        if (plotinfo->follow_unit > -1 && plotinfo->follow_unit != get_cur_unit_id()) {
            DEBUG(cycle,out).print("currently following unit {} that is not in history; adding\n", plotinfo->follow_unit);
            add_to_history(out, plotinfo->follow_unit);
        }

        int32_t id = unit->id;
        add_to_history(out, id);
        DEBUG(cycle,out).print("now following unit {}: {}\n", id, DF2CONSOLE(Units::getReadableName(unit)));
        Gui::revealInDwarfmodeMap(Units::getPosition(unit), false, World::ReadPauseState());
        plotinfo->follow_item = -1;
        plotinfo->follow_unit = id;
    }

    void scan_back(color_ostream &out) {
        if (history.empty() || offset >= history.size()-1) {