Use std::vector for the list of focused units

I would like to have some decent container to use in longturn#805 (if several units are
selected, I want the right click menu to apply to all of them, which will
require a container).

Change focus_units (=get_units_in_focus()) to be a std::vector<unit *>. This
has implications in a lot of places, which are also modified to use
std::vector.

client/citydlg.cpp

@@ -656,9 +656,6 @@ void unit_list_item::create_menu()
 
   m_menu = new QMenu;
 
-  auto *units = unit_list_new();
-  unit_list_append(units, m_unit);
-
   auto *activate_and_close_action = new QAction(_("Activate unit"), this);
   connect(activate_and_close_action, &QAction::triggered, this,
           &unit_list_item::activate_and_close_dialog);
@@ -693,35 +690,33 @@ void unit_list_item::create_menu()
     m_menu->addAction(change_homecity_action);
   }
 
-  if (units_can_load(units)) {
+  if (units_can_load({m_unit})) {
     auto *load_action = new QAction(_("Load"), this);
     connect(load_action, &QAction::triggered, this, &unit_list_item::load);
     m_menu->addAction(load_action);
   }
 
-  if (units_can_unload(units)) {
+  if (units_can_unload({m_unit})) {
     auto *unload_action = new QAction(_("Unload"), this);
     connect(unload_action, &QAction::triggered, this,
             &unit_list_item::unload);
     m_menu->addAction(unload_action);
   }
 
-  if (units_are_occupied(units)) {
+  if (units_are_occupied({m_unit})) {
     auto *unload_all_action =
         new QAction(_("Unload All From Transporter"), this);
     connect(unload_all_action, &QAction::triggered, this,
             &unit_list_item::unload_all);
     m_menu->addAction(unload_all_action);
   }
 
-  if (units_can_upgrade(units)) {
+  if (units_can_upgrade({m_unit})) {
     auto *upgrade_action = new QAction(_("Upgrade Unit"), this);
     connect(upgrade_action, &QAction::triggered, this,
             &unit_list_item::upgrade);
     m_menu->addAction(upgrade_action);
   }
-
-  unit_list_destroy(units);
 }
 
 /**
@@ -738,10 +733,7 @@ bool unit_list_item::can_issue_orders() const
 void unit_list_item::disband()
 {
   if (can_issue_orders()) {
-    auto *units = unit_list_new();
-    unit_list_append(units, m_unit);
-    popup_disband_dialog(units);
-    unit_list_destroy(units);
+    popup_disband_dialog({m_unit});
   }
 }
 
@@ -781,10 +773,7 @@ void unit_list_item::unload_all()
 void unit_list_item::upgrade()
 {
   if (can_issue_orders()) {
-    auto *units = unit_list_new();
-    unit_list_append(units, m_unit);
-    popup_upgrade_dialog(units);
-    unit_list_destroy(units);
+    popup_upgrade_dialog({m_unit});
   }
 }
 

client/client_main.cpp

@@ -916,7 +916,7 @@ void set_client_state(enum client_states newstate)
 
     update_info_label();
     unit_focus_update();
-    update_unit_info_label(nullptr);
+    update_unit_info_label({});
 
     break;
   }

client/climisc.cpp

@@ -17,6 +17,7 @@
 ***********************************************************************/
 
 #include <QBitArray>
+#include <algorithm>
 #include <cstdarg>
 #include <cstdlib>
 #include <cstring>
@@ -1054,19 +1055,13 @@ void cityrep_buy(struct city *pcity)
 /**
    Returns TRUE if any of the units can do the connect activity.
  */
-bool can_units_do_connect(struct unit_list *punits,
+bool can_units_do_connect(const std::vector<unit *> &units,
                           enum unit_activity activity,
                           struct extra_type *tgt)
 {
-  unit_list_iterate(punits, punit)
-  {
-    if (can_unit_do_connect(punit, activity, tgt)) {
-      return true;
-    }
-  }
-  unit_list_iterate_end;
-
-  return false;
+  return std::any_of(units.begin(), units.end(), [&](const auto unit) {
+    return can_unit_do_connect(unit, activity, tgt);
+  });
 }
 
 /**

client/climisc.h

@@ -95,7 +95,7 @@ struct city *get_nearest_city(const struct unit *punit, int *sq_dist);
 
 void cityrep_buy(struct city *pcity);
 
-bool can_units_do_connect(struct unit_list *punits,
+bool can_units_do_connect(const std::vector<unit *> &units,
                           enum unit_activity activity,
                           struct extra_type *tgt);