Refactor coordinate api into its own file

chunk_api.lua

@@ -0,0 +1,17 @@
+local CHUNK_SIZE = 16;
+
+-- Contains functions for converting coordinates between world units and the
+-- unit used by cartographer's maps
+return {
+    -- Convert world coordinates to map coordinates
+    -- coord: The coordinate value
+    to = function(coord)
+        return math.floor(coord / CHUNK_SIZE);
+    end,
+
+    -- Convert map coordinates to world coordinates
+    -- coord: The coordinate value
+    from = function(coord)
+        return math.floor(coord * CHUNK_SIZE);
+    end
+};

init.lua

@@ -1,8 +1,9 @@
-local mod_storage = minetest.get_mod_storage();
-
 -- The path to this mod, for including files
 local modpath = minetest.get_modpath("cartographer");
 
+
+-- Storage and saving
+local mod_storage = minetest.get_mod_storage();
 local map_data = {
     generated = minetest.deserialize(mod_storage:get_string("map")) or {},
 
@@ -28,20 +29,10 @@ local function periodic_save()
 end
 minetest.after(60, periodic_save);
 
-local chunk_size = 16;
-local chunk = {
-    to = function(coord)
-        return math.floor(coord / chunk_size);
-    end,
-
-    from = function(coord)
-        return math.floor(coord * chunk_size);
-    end
-};
-
 local marker_lookup = {};
 
 -- Includes
+local chunk = loadfile(modpath .. "/chunk_api.lua") ();
 local skin = loadfile(modpath .. "/skin_api.lua") ();
 local gui = loadfile(modpath .. "/formspec.lua") ();
 local audio = loadfile(modpath .. "/audio.lua") ();
@@ -61,10 +52,16 @@ loadfile(modpath .. "/autofill.lua") (chunk, scanner, maps);
 
 -- The API object
 cartographer = {
+    -- skin_api.lua: Allows the visual customization of formspecs
     skin = skin;
+    -- biome_api.lua: Allows biome data to be registered for display in maps
     biomes = biomes;
+    -- marker_api.lua: Allows markers to be registered for placement on maps
     markers = markers;
+    -- map_api.lua: Allows the creation, lookup, and management of map objects
     maps = maps;
+    -- items.lua: Allows the creation of map items with proper metadata
     map_item = map_item;
+    -- materials.lua: Allows items to be registered as mapmaking materials
     materials = materials;
 };