ne nw resize handle

* fix #2223

Author: adumesny

src/gridstack.scss

@@ -61,17 +61,25 @@ $animation_speed: .3s !default;
     &.ui-resizable-disabled > .ui-resizable-handle,
     &.ui-resizable-autohide > .ui-resizable-handle { display: none; }
 
+    > .ui-resizable-ne,
+    > .ui-resizable-nw,
     > .ui-resizable-se,
     > .ui-resizable-sw {
       background-image: url(data:image/svg+xml;base64,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);
       background-repeat: no-repeat;
       background-position: center;
     }
 
+    > .ui-resizable-ne {
+      @include vendor(transform, translate(0, 10px) rotate(45deg));
+    }
     > .ui-resizable-sw {
       @include vendor(transform, rotate(45deg));
     }
 
+    > .ui-resizable-nw {
+      @include vendor(transform, translate(0, 10px) rotate(-45deg));
+    }
     > .ui-resizable-se {
       @include vendor(transform, rotate(-45deg));
     }