Add gunpowder trails

Uses group “connect_to_raillike”

game_api.txt

@@ -218,6 +218,8 @@ Use `minetest.raillike_group(<Name>)` to get the group value.
 | Node type		| Raillike group name
 +-----------------------+----------------------------------
 | default:rail		| "rail"
+| tnt:gunpowder		| "gunpowder"
+| tnt:gunpowder_burning	| "gunpowder"
 
 Example:
 If you want to add a new rail type and want it to connect with default:rail,

mods/tnt/init.lua

@@ -270,14 +270,14 @@ minetest.register_node("tnt:gunpowder", {
 	paramtype = "light",
 	sunlight_propagates = true,
 	walkable = false,
-	tiles = {"tnt_gunpowder.png",},
+	tiles = {"tnt_gunpowder_straight.png", "tnt_gunpowder_curved.png", "tnt_gunpowder_t_junction.png", "tnt_gunpowder_crossing.png"},
 	inventory_image = "tnt_gunpowder_inventory.png",
 	wield_image = "tnt_gunpowder_inventory.png",
 	selection_box = {
 		type = "fixed",
 		fixed = {-1/2, -1/2, -1/2, 1/2, -1/2+1/16, 1/2},
 	},
-	groups = {dig_immediate=2,attached_node=1},
+	groups = {dig_immediate=2,attached_node=1,connect_to_raillike=minetest.raillike_group("gunpowder")},
 	sounds = default.node_sound_leaves_defaults(),
 	
 	on_punch = function(pos, node, puncher)
@@ -297,7 +297,34 @@ minetest.register_node("tnt:gunpowder_burning", {
 	walkable = false,
 	light_source = 5,
 	tiles = {{
-		name = "tnt_gunpowder_burning_animated.png",
+		name = "tnt_gunpowder_burning_straight_animated.png",
+		animation = {
+			type = "vertical_frames",
+			aspect_w = 16,
+			aspect_h = 16,
+			length = 1,
+		}
+	},
+	{
+		name = "tnt_gunpowder_burning_curved_animated.png",
+		animation = {
+			type = "vertical_frames",
+			aspect_w = 16,
+			aspect_h = 16,
+			length = 1,
+		}
+	},
+	{
+		name = "tnt_gunpowder_burning_t_junction_animated.png",
+		animation = {
+			type = "vertical_frames",
+			aspect_w = 16,
+			aspect_h = 16,
+			length = 1,
+		}
+	},
+	{
+		name = "tnt_gunpowder_burning_crossing_animated.png",
 		animation = {
 			type = "vertical_frames",
 			aspect_w = 16,
@@ -310,7 +337,7 @@ minetest.register_node("tnt:gunpowder_burning", {
 		fixed = {-1/2, -1/2, -1/2, 1/2, -1/2+1/16, 1/2},
 	},
 	drop = "",
-	groups = {dig_immediate=2,attached_node=1},
+	groups = {dig_immediate=2,attached_node=1,connect_to_raillike=minetest.raillike_group("gunpowder")},
 	sounds = default.node_sound_leaves_defaults(),
 	on_timer = function(pos, elapsed)
 		for dx = -1, 1 do