unify board image naming

ui/common/css/vendor/chessground/_board-2d.scss

@@ -6,7 +6,7 @@ $board-files: (
   'blue-marble': 'blue-marble.jpg',
   'wood2': 'wood2.jpg',
   'wood3': 'wood3.jpg',
-  'wood4': 'wood4-1024.jpg',
+  'wood4': 'wood4.jpg',
   'blue3': 'blue3.jpg',
   'marble': 'marble.jpg',
   'brown': 'svg/brown.svg',
@@ -16,10 +16,10 @@ $board-files: (
   'purple': 'svg/purple.svg',
   'purple-diag': 'purple-diag.png',
   'grey': 'grey.jpg',
-  'wood': 'wood-1024.jpg',
-  'canvas': 'canvas2-1024.jpg',
-  'leather': 'leather-1024.jpg',
-  'metal': 'metal-1024.jpg',
+  'wood': 'wood.jpg',
+  'canvas': 'canvas2.jpg',
+  'leather': 'leather.jpg',
+  'metal': 'metal.jpg',
   'maple': 'maple.jpg',
   'maple2': 'maple2.jpg',
   'newspaper': 'newspaper.png',

ui/dasher/css/_piece.scss

@@ -16,7 +16,7 @@
     .list {
       @extend %flex-wrap;
 
-      background: url(../images/board/darksquares.jpg);
+      background: url(../images/darksquares.jpg);
       box-shadow: inset 0 7px 20px 3px #777;
     }