Organize builtin into subdirectories

builtin/game/features.lua

@@ -0,0 +1,29 @@
+-- Minetest: builtin/features.lua
+
+minetest.features = {
+	glasslike_framed = true,
+	nodebox_as_selectionbox = true,
+	chat_send_player_param3 = true,
+	get_all_craft_recipes_works = true,
+	use_texture_alpha = true,
+	no_legacy_abms = true,
+}
+
+function minetest.has_feature(arg)
+	if type(arg) == "table" then
+		missing_features = {}
+		result = true
+		for ft, _ in pairs(arg) do
+			if not minetest.features[ftr] then
+				missing_features[ftr] = true
+				result = false
+			end
+		end
+		return result, missing_features
+	elseif type(arg) == "string" then
+		if not minetest.features[arg] then
+			return false, {[arg]=true}
+		end
+		return true, {}
+	end
+end