Add autocouple mode

The shunting mode no longer makes trains couple, since it was meant
for other purposes. For autocoupling, the new autocoupling mode is
used. If trains are in autocouple mode, they couple when they collide
with another train.

advtrains/init.lua

@@ -392,7 +392,7 @@ advtrains.avt_save = function(remove_players_from_wagons)
 				"trainparts", "recently_collided_with_env",
 				"atc_brake_target", "atc_wait_finish", "atc_command", "atc_delay", "door_open",
 				"text_outside", "text_inside", "line", "routingcode",
-				"il_sections", "speed_restriction", "is_shunt", "points_split",
+				"il_sections", "speed_restriction", "is_shunt", "points_split", "autocouple"
 			})
 			--then save it
 			tmp_trains[id]=v

advtrains/trainlogic.lua

@@ -906,7 +906,7 @@ function advtrains.split_train_at_index(train, index)
 		atwarn("Train",train_id,"is not initialized! Operation aborted!")
 		return
 	end
-	train.is_shunt = nil -- prevent immediate recoupling
+
 	local p_index=advtrains.path_get_index_by_offset(train, train.index, - data.pos_in_train + wagon.wagon_span)
 	local pos, connid, frac = advtrains.path_getrestore(train, p_index)
 	local tp = {}
@@ -944,10 +944,10 @@ local CPL_ZONE = 2
 local function createcouple(pos, train1, t1_is_front, train2, t2_is_front)
 	local id1 = train1.id
 	local id2 = train2.id
-	if train1.is_shunt or train2.is_shunt then
+	if train1.autocouple or train2.autocouple then
 		-- couple trains
-		train1.is_shunt = nil
-		train2.is_shunt = nil		
+		train1.autocouple = nil
+		train2.autocouple = nil		
 		minetest.after(0, advtrains.safe_couple_trains, id1, id2, t1_is_front, t2_is_front, false, false, train1.velocity, train2.velocity)
 		return
 	end

advtrains_luaautomation/README.txt

@@ -203,10 +203,12 @@ set_rc(routingcode)
 split_at_index(index, command)
 	Splits the train at the specified index, into a train with index-1 wagons and a second train starting with the index-th wagon.
 	command specifies an atc command to be sent to the second train after decoupling. 
-set_shunt()
-	Sets the train into shunting mode
-unset_shunt()
-	Sets the train into normal mode
+set_autocouple()
+	Sets the train into autocouple mode 
+unset_autocouple()
+	Unsets autocouple mode
+set_shunt(), unset_shunt()
+	deprecated aliases for set_autocouple() and unset_autocouple(), will be removed from a later release.
 
 # Operator panel
 This simple node executes its actions when punched. It can be used to change a switch and update the corresponding signals or similar applications.

advtrains_luaautomation/atc_rail.lua

@@ -67,13 +67,20 @@ function r.fire_event(pos, evtdata)
 			return false
 		end,
 		set_shunt = function()
-			-- enable shunting mode
 			if not train_id then return false end
-			train.is_shunt = true
+			train.autocouple = true
 		end,
 		unset_shunt = function()
 			if not train_id then return false end
-			train.is_shunt = nil
+			train.autocouple = nil
+		end,
+		set_autcouple = function ()
+			if not train_id then return false end
+			train.autocouple = true			
+		end,
+		unset_autocouple = function ()
+			if not train_id then return false end
+			train.autocouple = nil
 		end,
 		set_line = function(line)
 			if type(line)~="string" and type(line)~="number" then