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

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

@@ -0,0 +1,12 @@
+package org.bukkit.inventory;
+
+/**
+ * Represents some type of crafting recipe.
+ */
+public interface Recipe {
+    /**
+     * Get the result of this recipe.
+     * @return The result stack
+     */
+    ItemStack getResult();
+}