Fix robots healing from being thrown

Author: erasedbird

engine/src/main/battlecode/world/InternalRobot.java

@@ -743,7 +743,7 @@ public void hitGround() {
 
     public void hitTarget(boolean isSecondMove) {
         int damage = GameConstants.THROW_DAMAGE
-                - GameConstants.THROW_DAMAGE_PER_TILE * (2 * this.remainingThrowDuration + (isSecondMove ? 0 : 1));
+                + GameConstants.THROW_DAMAGE_PER_TILE * (2 * this.remainingThrowDuration + (isSecondMove ? 0 : 1));
 
         if (this.gameWorld.getRobot(this.getLocation().add(this.thrownDir)) != null) {
             InternalRobot robot = this.gameWorld.getRobot(this.getLocation().add(this.thrownDir));