Add recipe classes and an addRecipe method in the server interface.

src/main/java/org/bukkit/inventory/FurnaceRecipe.java

@@ -0,0 +1,73 @@
+package org.bukkit.inventory;
+
+import org.bukkit.Material;
+import org.bukkit.material.MaterialData;
+
+/**
+ * Represents a smelting recipe.
+ */
+public class FurnaceRecipe implements Recipe {
+    private ItemStack output;
+    private MaterialData ingredient;
+
+    /**
+     * Create a furnace recipe to craft the specified ItemStack.
+     * @param result The item you want the recipe to create.
+     * @param source The input material.
+     */
+    public FurnaceRecipe(ItemStack result, Material source) {
+        this(result, source.getNewData((byte) 0));
+        if (this.ingredient == null) {
+            setInput(new MaterialData(source));
+        }
+    }
+
+    /**
+     * Create a furnace recipe to craft the specified ItemStack.
+     * @param result The item you want the recipe to create.
+     * @param source The input material.
+     */
+    public FurnaceRecipe(ItemStack result, MaterialData source) {
+        this.output = result;
+        this.ingredient = source;
+    }
+
+    /**
+     * Sets the input of this furnace recipe.
+     * @param input The input material.
+     * @return The changed recipe, so you can chain calls.
+     */
+    public FurnaceRecipe setInput(MaterialData input) {
+        this.ingredient = input;
+        return this;
+    }
+
+    /**
+     * Sets the input of this furnace recipe.
+     * @param input The input material.
+     * @return The changed recipe, so you can chain calls.
+     */
+    public FurnaceRecipe setInput(Material input) {
+        setInput(input.getNewData((byte) 0));
+        if (this.ingredient == null) {
+            setInput(new MaterialData(input));
+        }
+        return this;
+    }
+
+    /**
+     * Get the input material.
+     * @return The input material.
+     */
+    public MaterialData getInput() {
+        return (MaterialData) ingredient;
+    }
+
+    /**
+     * Get the result of this recipe.
+     * @return The resulting stack.
+     */
+    public ItemStack getResult() {
+        return output;
+    }
+}