Implement target-tile selection and Shift-queueing for all unit actions

unit.h

@@ -35,8 +35,8 @@ struct UnitAction {
 
     UnitAction() = default;
     UnitAction(UnitActionType t) : type(t) {}
-    UnitAction(UnitActionType t, int x, int y, const QString &data = "")
-        : type(t), targetX(x), targetY(y), extraData(data) {}
+    UnitAction(UnitActionType t, int x, int y, const QString &data = "", int uId = -1)
+        : type(t), targetX(x), targetY(y), targetUnitId(uId), extraData(data) {}
     UnitAction(UnitActionType t, int targetId)
         : type(t), targetUnitId(targetId) {}
 
@@ -65,9 +65,10 @@ public:
     int targetTileX;
     int targetTileY;
 
-    // Action Queue
+    // Currently executing action & subsequent Action Queue
+    UnitAction currentAction;
     std::deque<UnitAction> actionQueue;
-    int maxQueueSize = 5;
+    int maxQueueSize = 15;
 
     // Road Construction Route (tile-by-tile road paving)
     std::vector<std::pair<int, int>> roadRoute;
@@ -88,13 +89,20 @@ public:
         }
     }
 
+    bool hasActiveAction() const {
+        return currentAction.isValid() || state != UnitState::Idle || hasRoadRoute();
+    }
+
     bool queueAction(const UnitAction &action);
     void clearActionQueue();
     bool hasQueuedAction() const { return !actionQueue.empty(); }
     bool hasQueuedActionType(UnitActionType type) const;
+    bool hasQueuedImprovementAt(int tx, int ty) const;
+    bool hasQueuedCityAt(int tx, int ty) const;
     void removeQueuedActionsOfType(UnitActionType type);
     UnitAction popNextQueuedAction();
     const UnitAction* peekNextQueuedAction() const;
+    QString getActionSummary(const UnitAction &act) const;
     QString getQueuedActionSummary() const;
 
     // Attack cooldown / flash