Update test_defaults_and_patches implementation, assets and documentation

patches/item.json

@@ -9,6 +9,26 @@
       "Id": "*",
       "Durability": 50,
       "GlobalItemProp": "patched"
+    },
+    {
+      "Id": "FOOD/WOLF_MEAT",
+      "Cost": 77
+    },
+    {
+      "Id": "food/wolf_meat",
+      "Cost": "many"
+    },
+    {
+      "Id": "food/wolf_meat",
+      "Name$add": ["broken"]
+    },
+    {
+      "Id": "test_patches/base",
+      "Sprite": "food/wolf_meat"
+    },
+    {
+      "Id": "test_patches/doomed",
+      "$delete": true
     }
   ]
 }

patches/item/explain.json

@@ -0,0 +1,8 @@
+{
+  "Items": [
+    {
+      "Id": "test_patches/child",
+      "Description": "items/food/wolf_meat/desc"
+    }
+  ]
+}