cleaner children/undo view and show regardless of eval

config.json

@@ -17,8 +17,8 @@
     "stones": [ [0.05, 0.05, 0.05], [0.95, 0.95, 0.95] ],
     "ghost_alpha": 0.5,
     "eval_colors": [[0.537, 0.129, 0.42], [1, 0, 0], [1, 0.95, 0], [0.117, 0.588, 0]],
-    "undo_circle_col": [0.88,0.02,0.17,0.5],
-    "undo_alpha": 0.5,	
+    "undo_alpha": 0.5,
+    "undo_scale": 0.95,
     "eval_knots": [0, 0.5, 0.875, 1],
     "eval_bounds": [1,12],
     "board_margin": 1.5,