Add a very brief description at the head of every file

compatibility.lua

@@ -1,3 +1,6 @@
+-- Fix compatibility for settings-related changes
+-- Only loaded if the versions of the mod and the world mismatch
+
 local function version_is_lower(v1, v2)
 	local d1, c1, d2, c2
 	while #v1 > 0 and #v2 > 0 do

gridio.lua

@@ -1,3 +1,5 @@
+-- Input and output functions for grid maps
+
 local worldpath = mapgen_rivers.world_data_path
 
 local floor = math.floor

gridmanager.lua

@@ -1,3 +1,5 @@
+-- Manages grid loading, writing and generation
+
 local world_data = mapgen_rivers.world_data_path
 
 local registered_on_grid_loaded = {}

heightmap.lua

@@ -1,3 +1,5 @@
+-- Transform polygon data into a heightmap
+
 local modpath = mapgen_rivers.modpath
 
 local sea_level = mapgen_rivers.settings.sea_level

init.lua

@@ -1,3 +1,5 @@
+-- Main file, calls the other files and triggers main functions
+
 mapgen_rivers = {}
 
 local modpath = minetest.get_modpath(minetest.get_current_modname()) .. '/'

mapgen.lua

@@ -1,3 +1,5 @@
+-- Mapgen loop and mapgen-related things
+
 if minetest.get_mapgen_setting("mg_name") ~= "singlenode" then
 	minetest.set_mapgen_setting("mg_name", "singlenode", true)
 	minetest.log("warning", "[mapgen_rivers] Mapgen set to singlenode")

polygons.lua

@@ -1,3 +1,6 @@
+-- Fetch polygons from a given areas, and compute their properties
+-- and find to which polygon every point belongs
+
 local blocksize = mapgen_rivers.settings.blocksize
 local X = math.floor(mapgen_rivers.settings.map_x_size / blocksize)
 local Z = math.floor(mapgen_rivers.settings.map_z_size / blocksize)

pregenerate.lua

@@ -1,3 +1,6 @@
+-- Generate the grid using terrainlib_lua
+-- Only called on first mapgen, if there is no grid yet
+
 local EvolutionModel = dofile(mapgen_rivers.modpath .. '/terrainlib_lua/erosion.lua')
 local twist = dofile(mapgen_rivers.modpath .. '/terrainlib_lua/twist.lua')
 

settings.lua

@@ -1,3 +1,5 @@
+-- Read global and per-world settings
+
 local mtsettings = minetest.settings
 local mgrsettings = Settings(minetest.get_worldpath() .. '/mapgen_rivers.conf')