add api.txt and tidy code

api.txt

@@ -0,0 +1,41 @@
+Farming API
+-----------
+
+The farming API allows you to easily register plants and hoes.
+
+`farming.register_hoe(name, hoe definition)`
+ * Register a new hoe, see [#hoe definition]
+
+`farming.register_plant(name, Plant definition)`
+ * Register a new growing plant, see [#Plant definition]
+
+`farming.registered_plants[name] = definition`
+ * Table of registered plants, indexed by plant name
+
+### Hoe Definition
+
+
+	{
+		description = "",                      -- Description for tooltip
+		inventory_image = "unknown_item.png",  -- Image to be used as wield- and inventory image
+		max_uses = 30,                         -- Uses until destroyed
+		material = "",                         -- Material for recipes
+		recipe = {                             -- Craft recipe, if material isn't used
+			{"air", "air", "air"},
+			{"", "group:stick"},
+			{"", "group:stick"},
+		}
+	}
+
+### Plant definition
+
+	{
+		description = "",                      -- Description of seed item
+		inventory_image = "unknown_item.png",  -- Image to be used as seed's wield- and inventory image
+		steps = 8,                             -- How many steps the plant has to grow, until it can be harvested
+		-- ^ Always provide a plant texture for each step, format: modname_plantname_i.png (i = stepnumber)
+		minlight = 13,                         -- Minimum light to grow
+		maxlight = default.LIGHT_MAX           -- Maximum light to grow
+	}
+
+Note: Any crops registered with the above function will use the new growing routines, also if crops are manually added with the {growing=1} group they will also grow.