Added guard attack

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

lib/classes/entity.dart

@@ -7,6 +7,7 @@ class Entity {
   double angle;
   EntityState state;
   int mapId;
+  int lastActionTime;
 
   Entity({
     required this.x,
@@ -15,5 +16,6 @@ class Entity {
     this.angle = 0.0,
     this.state = EntityState.staticObj,
     this.mapId = 0,
+    this.lastActionTime = 0,
   });
 }