[gnome-2048] Fix score.

[Arnaud B. <arnaudb src gnome org>]

commit 972238e5f7001e6aeadc830f4d54ca4e816c1805
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Wed Feb 6 13:56:05 2019 +0100

    Fix score.
    
    Regression from 0f3b7582f3.

 src/game.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/game.vala b/src/game.vala
index 1bce5c3..4cc0706 100644
--- a/src/game.vala
+++ b/src/game.vala
@@ -531,7 +531,7 @@ private class Game : Object
                 assert_not_reached ();
             _create_tile ((!) e);
             _show_tile (((!) e).pos);
-            delta_score += ((!) e).val;
+            delta_score += (uint) Math.pow (2, ((!) e).val);
         }
         score += delta_score;
         _store_score_update (delta_score);