Send digiline messages after luacontroller execution

In the same way as for port settings, this queues up digiline messages
sent during the luacontroller's execution, and sends them afterwards.
This solves many problems, but one example:

1. Send a message, and receive a reply from another device.
2. While handling the reply event (effectively a nested invocation
   on the same luacontroller) make a change to memory
3. Notice that the memory change has no effect, because after
   completion of the reply handling, it stores the memory, but then
   the original invocation completes and overwrites it with it's
   own earlier copy of the same memory.

mesecons_luacontroller/init.lua

@@ -2,7 +2,7 @@
 -- ports = get_real_portstates(pos): gets if inputs are powered from outside
 -- newport = merge_portstates(state1, state2): just does result = state1 or state2 for every port
 -- action_setports(pos, rule, state): activates/deactivates the mesecons according to the portstates (helper for action)
--- action(pos, ports): Applies new portstates to a luacontroller at pos
+-- action(pos, ports, digiline_msgs): Applies new portstates to a luacontroller at pos, and sends pending digiline messages
 -- lc_update(pos): updates the controller at pos by executing the code
 -- reset_meta (pos, code, errmsg): performs a software-reset, installs new code and prints error messages
 -- reset (pos): performs a hardware reset, turns off all ports
@@ -99,7 +99,7 @@ local setport = function (pos, rule, state)
 	end
 end
 
-local action = function (pos, ports)
+local action = function (pos, ports, digiline_msgs)
 	local node = minetest.get_node(pos)
 	local name = node.name
 	local vports = minetest.registered_nodes[name].virtual_portstates
@@ -116,6 +116,13 @@ local action = function (pos, ports)
 		if ports.c ~= vports.c then setport(pos, rules.c, ports.c) end
 		if ports.d ~= vports.d then setport(pos, rules.d, ports.d) end
 	end
+
+	if digiline then
+		for i = 1, #digiline_msgs do
+			digiline:receptor_send(pos, digiline.rules.default,
+			    digiline_msgs[i].channel, digiline_msgs[i].msg)
+		end
+	end
 end
 
 --------------------
@@ -219,15 +226,6 @@ local getinterrupt = function(pos)
 	return interrupt
 end
 
-local getdigiline_send = function (pos)
-	local digiline_send = function (channel, msg)
-		if digiline then
-			digiline:receptor_send(pos, digiline.rules.default, channel, msg)
-		end
-	end
-	return digiline_send
-end
-
 local create_environment = function(pos, mem, event)
 	-- Gather variables for the environment
 	local vports = minetest.registered_nodes[minetest.get_node(pos).name].virtual_portstates
@@ -239,7 +237,10 @@ local create_environment = function(pos, mem, event)
 			pin = merge_portstates(vports, rports),
 			port = vports,
 			interrupt = getinterrupt(pos),
-			digiline_send = getdigiline_send(pos),
+			digiline_msgs = {},
+			digiline_send = function(channel, msg)
+				table.insert(lc_digiline_msgs, {["channel"]=channel, ["msg"]=msg})
+			end,
 			mem = mem,
 			tostring = tostring,
 			tonumber = tonumber,
@@ -356,6 +357,7 @@ end
 -- Parsing function --
 ----------------------
 
+lc_digiline_msgs = nil
 lc_update = function (pos, event)
 	local meta = minetest.get_meta(pos)
 	if not interrupt_allow(meta, event) then return end
@@ -371,6 +373,7 @@ lc_update = function (pos, event)
 	local env = create_environment(pos, mem, event)
 
 	-- create the sandbox and execute code
+	lc_digiline_msgs = {}
 	local chunk, msg = create_sandbox (code, env)
 	if not chunk then return msg end
 	local success, msg = pcall(f)
@@ -379,8 +382,8 @@ lc_update = function (pos, event)
 
 	save_memory(meta, mem)
 
-	-- Actually set the ports
+	-- Actually set the ports and send digiline messages
-	minetest.after(0, action, pos, env.port)
+	minetest.after(0, action, pos, env.port, lc_digiline_msgs)
 end
 
 local reset_meta = function(pos, code, errmsg)
@@ -399,7 +402,7 @@ end
 
 local reset = function (pos)
 	minetest.get_meta(pos):set_string("lc_interrupts", "")
-	action(pos, {a=false, b=false, c=false, d=false}, true)
+	action(pos, {a=false, b=false, c=false, d=false}, {})
 end
 
 --        ______