Add isDone() boolean method to Accident

isDone() checks all invovlved CivilVehicles
	in Accident instance. If any car has reference
	to 'this' then it is still not done.
	Done would be true if fix() of each car is invoked.

Signed-off-by: HeshamTB <hishaminv@gmail.com>

src/Accident.java

@@ -41,4 +41,19 @@ public class Accident {
         }
         return max;
     }
+
+    public boolean isDone(){
+        for (Breakable car : this.involvedCars){
+            /*
+            if broken flag is set and currAcc is ref to this instance
+            then the accident is not done.
+            The ref to accident should be null if fix() of car is invoked
+             */
+            if (car.isBroken() &&
+                    ((CivilVehicle)car).getCurrentAccident() == this) {
+                return false;
+            }
+        }
+        return true;
+    }
 }