Add ATC "K" command

This command kicks out all passengers when the train is stopped and
its doors are open. In addtion, a wagon:is_driver_stand(seat) function
was added to allow finding out easily if a seat is the driver stand of
the wagon.

advtrains/atc.lua

@@ -230,6 +230,32 @@ local matchptn={
 		train.door_open = tt[match]*arr
 		return 2
 	end,
+	["K"] = function(id, train)
+		if train.door_open == 0 then
+			atwarn(sid(id), attrans("ATC Kick command warning: Doors closed"))
+			return 1
+		end
+		if train.velocity > 0 then
+			atwarn(sid(id), attrans("ATC Kick command warning: Train moving"))
+			return 1
+		end
+		local tp = train.trainparts
+		for i=1,#tp do
+			local data = advtrains.wagons[tp[i]]
+			local obj = advtrains.wagon_objects[tp[i]]
+			if data and obj then
+				local ent = obj:get_luaentity()
+				if ent then
+					for seatno,seat in pairs(ent.seats) do
+						if data.seatp[seatno] and not ent:is_driver_stand(seat) then
+							ent:get_off(seatno)
+						end
+					end
+				end
+			end
+		end
+		return 1
+	end,
 }
 
 eval_conditional = function(command, arrow, speed)

advtrains/wagons.lua

@@ -269,6 +269,15 @@ function wagon:destroy()
 	return true
 end
 
+function wagon:is_driver_stand(seat)
+	if self.seat_groups then
+		return (seat.driving_ctrl_access or self.seat_groups[seat.group].driving_ctrl_access)
+	else
+		return seat.driving_ctrl_access
+	end
+	
+end
+
 function wagon:on_step(dtime)
 	return advtrains.pcall(function()
 		if not self:ensure_init() then return end
@@ -301,11 +310,7 @@ function wagon:on_step(dtime)
 			local pname=data.seatp[seatno]
 			local driver=pname and minetest.get_player_by_name(pname)
 			local has_driverstand = pname and advtrains.check_driving_couple_protection(pname, data.owner, data.whitelist)
-			if self.seat_groups then
-				has_driverstand = has_driverstand and (seat.driving_ctrl_access or self.seat_groups[seat.group].driving_ctrl_access)
-			else
-				has_driverstand = has_driverstand and (seat.driving_ctrl_access)
-			end
+			has_driverstand = has_driverstand and self:is_driver_stand(seat)
 			if has_driverstand and driver then
 				advtrains.update_driver_hud(driver:get_player_name(), self:train(), data.wagon_flipped)
 			elseif driver then

atc_command.txt

@@ -46,6 +46,11 @@ Example:
 B0 W OL D10 OC D1 SM
 Subway train: stop in station and open doors, depart after 10 seconds.
 
+K
+Kick all passengers out of the trains
+This command kicks all passengers (non-driving players) off the train. This command works only
+if the train is stopped and its doors are open.
+
 # conditional statements:
 
 I<condition><code>;