Add chests, the beginnings of a machines API, and other things

mods/rgt_materials/init.lua

@@ -1,10 +1,29 @@
 
+--[[
+    Minimum features needed to make this a playable game:
+    - Basic towns
+      - Covered wagon
+    - Machines
+      - 
+    - Materials
+      - Diamond
+    - Biomes
+      - Ocean
+    - Decoration nodes
+      - Stone bricks
+      - Stone tile (default stone block)
+      - Sand
+      - Gravel
+--]]
+
 rgt.register_item("iron_ingot", {
     inventory_image = "rgt_iron_ingot.png",
+    groups = {furnace_fuel = 1}
 })
 
 rgt.register_item("iron_lump", {
     inventory_image = "rgt_iron_lump.png",
+    groups = {furnace_smeltable = 1}
 })
 
 rgt.register_node("iron_block", {