Switch to icon composer source. (#714)

Design/Icon.icon/icon.json

@@ -1,59 +0,0 @@
-{
-  "fill" : {
-    "solid" : "srgb:0.00000,0.53333,1.00000,0.00000"
-  },
-  "groups" : [
-    {
-      "blur-material" : 0.5,
-      "layers" : [
-        {
-          "image-name" : "Icon 7.png",
-          "name" : "Signature",
-          "position" : {
-            "scale" : 1,
-            "translation-in-points" : [
-              64.00083178971097,
-              -58.21801551632592
-            ]
-          }
-        },
-        {
-          "image-name" : "Rectangle Copy 10.png",
-          "name" : "Border"
-        },
-        {
-          "fill-specializations" : [
-            {
-              "appearance" : "tinted",
-              "value" : {
-                "solid" : "display-p3:0.00000,0.00000,0.00000,0.50000"
-              }
-            }
-          ],
-          "image-name" : "Rectangle 2 8.png",
-          "name" : "Backing",
-          "opacity-specializations" : [
-            {
-              "appearance" : "tinted",
-              "value" : 1
-            }
-          ]
-        }
-      ],
-      "shadow" : {
-        "kind" : "layer-color",
-        "opacity" : 0.5
-      },
-      "specular" : true,
-      "translucency" : {
-        "enabled" : true,
-        "value" : 0.5
-      }
-    }
-  ],
-  "supported-platforms" : {
-    "squares" : [
-      "macOS"
-    ]
-  }
-}