Removed backward comp fix for monarch.back()

Fixes #102

README_TRANSITIONS.md

@@ -114,7 +114,7 @@ end
 
 function on_message(self, message_id, message, sender)
 	if message_id == hash("my_resize_message") then
-		self.transition.window_resized(message.width, message.height)
+		transition.window_resized(message.width, message.height)
 	end
 end
 ```

example/advanced/confirm.gui_script

@@ -29,7 +29,7 @@ function on_input(self, action_id, action)
 			end
 		elseif gui.pick_node(self.no, action.x, action.y) then
 			print("no")
-			monarch.back(function()
+			monarch.back(nil, nil, function()
 				print("back from popup done")
 			end)
 		end

example/advanced/popup.gui_script

@@ -27,7 +27,7 @@ function on_input(self, action_id, action)
 			end)
 		elseif gui.pick_node(self.cancel, action.x, action.y) then
 			print("cancel")
-			monarch.back(function()
+			monarch.back(nil, nil, function()
 				print("back from popup done")
 			end)
 		elseif gui.pick_node(self.about, action.x, action.y) then

example/advanced/pregame.gui_script

@@ -19,7 +19,7 @@ function on_input(self, action_id, action)
 			end)
 		elseif gui.pick_node(self.back, action.x, action.y) then
 			print("back")
-			monarch.back(function()
+			monarch.back(nil, nil, function()
 				print("back from pregame done")
 			end)
 		end

monarch/monarch.lua

@@ -520,8 +520,12 @@ local function load(screen)
 		msg.post(screen.proxy, MSG_ENABLE)
 	elseif screen.factory then
 		screen.factory_ids = collectionfactory.create(screen.factory)
-		screen.transition_url = screen.factory_ids[screen.transition_id]
-		screen.focus_url = screen.factory_ids[screen.focus_id]
+		if screen.transition_id then
+			screen.transition_url = screen.factory_ids[screen.transition_id]
+		end
+		if screen.focus_id then
+			screen.focus_url = screen.factory_ids[screen.focus_id]
+		end
 	end
 	screen.loaded = true
 	screen.preloaded = false
@@ -920,7 +924,7 @@ function M.hide(id, cb)
 			log("hide() you can only hide the screen at the top of the stack", id)
 			return false
 		end
-		return M.back(id, cb)
+		return M.back(nil, nil, cb)
 	else
 		log("hide() queuing action", id)
 		queue_action(function(action_done, action_error)
@@ -982,17 +986,6 @@ end
 -- @param cb (function) - Optional callback to invoke when the previous screen is visible again
 function M.back(options, data, cb)
 	log("back() queuing action")
-	-- backwards compatibility with old version M.back(data, cb)
-	-- case when back(data, cb)
-	if type(data) == "function" then
-		cb = data
-		data = options
-		options = nil
-	-- case when back(data, nil)
-	elseif options ~= nil and data == nil and cb == nil then
-		data = options
-		options = nil
-	end
 
 	queue_action(function(action_done)
 		local callbacks = callback_tracker()