Farming: Deprecate bronze, mese and diamond hoes. Tune steel uses (#2103)

Remove unnecessary "air" fallback recipe for hoes to avoid this showing
in crafting guides.

mods/farming/api.lua

@@ -83,13 +83,6 @@ farming.register_hoe = function(name, def)
 	if def.inventory_image == nil then
 		def.inventory_image = "unknown_item.png"
 	end
-	if def.recipe == nil then
-		def.recipe = {
-			{"air","air",""},
-			{"","group:stick",""},
-			{"","group:stick",""}
-		}
-	end
 	if def.max_uses == nil then
 		def.max_uses = 30
 	end
@@ -104,12 +97,12 @@ farming.register_hoe = function(name, def)
 		sound = {breaks = "default_tool_breaks"},
 	})
 	-- Register its recipe
-	if def.material == nil then
+	if def.recipe then
 		minetest.register_craft({
 			output = name:sub(2),
 			recipe = def.recipe
 		})
-	else
+	elseif def.material then
 		minetest.register_craft({
 			output = name:sub(2),
 			recipe = {

mods/farming/hoes.lua

@@ -16,27 +16,32 @@ farming.register_hoe(":farming:hoe_stone", {
 farming.register_hoe(":farming:hoe_steel", {
 	description = "Steel Hoe",
 	inventory_image = "farming_tool_steelhoe.png",
-	max_uses = 200,
+	max_uses = 500,
 	material = "default:steel_ingot"
 })
 
+-- The following are deprecated by removing the 'material' field to prevent
+-- crafting and removing from creative inventory, to cause them to eventually
+-- disappear from worlds. The registrations should be removed in a future
+-- release.
+
 farming.register_hoe(":farming:hoe_bronze", {
 	description = "Bronze Hoe",
 	inventory_image = "farming_tool_bronzehoe.png",
 	max_uses = 220,
-	material = "default:bronze_ingot"
+	groups = {not_in_creative_inventory = 1},
 })
 
 farming.register_hoe(":farming:hoe_mese", {
 	description = "Mese Hoe",
 	inventory_image = "farming_tool_mesehoe.png",
 	max_uses = 350,
-	material = "default:mese_crystal"
+	groups = {not_in_creative_inventory = 1},
 })
 
 farming.register_hoe(":farming:hoe_diamond", {
 	description = "Diamond Hoe",
 	inventory_image = "farming_tool_diamondhoe.png",
 	max_uses = 500,
-	material = "default:diamond"
+	groups = {not_in_creative_inventory = 1},
 })