sam do not target twice same nuke (#270)

src/core/game/Game.ts

@@ -244,6 +244,9 @@ export interface Unit {
   setMoveTarget(cell: TileRef): void;
   moveTarget(): TileRef | null;
 
+  setTargetedBySAM(targeted: boolean): void;
+  targetedBySAM(): boolean;
+
   // Mutations
   setTroops(troops: number): void;
   delete(displayerMessage?: boolean): void;

src/core/game/UnitImpl.ts

@@ -15,10 +15,11 @@ export class UnitImpl implements Unit {
   // Currently only warship use it
   private _target: Unit = null;
   private _moveTarget: TileRef = null;
+  private _targetedBySAM = false;
 
   private _constructionType: UnitType = undefined;
 
-  private _isSamCooldown: boolean;
+  private _isSamCooldown: boolean = false;
   private _dstPort: Unit | null = null; // Only for trade ships
   private _detonationDst: TileRef | null = null; // Only for nukes
   private _warshipTarget: Unit | null = null;
@@ -204,4 +205,12 @@ export class UnitImpl implements Unit {
   moveTarget(): TileRef | null {
     return this._moveTarget;
   }
+
+  setTargetedBySAM(targeted: boolean): void {
+    this._targetedBySAM = targeted;
+  }
+
+  targetedBySAM(): boolean {
+    return this._targetedBySAM;
+  }
 }