Remove some long unused legacy code

The change that required this compatibility layer happened in
2014, so other mods have had a lot of time to update.

mesecons/legacy.lua

--- Ugly hack to prevent breaking compatibility with other mods
--- Just remove the following two functions to delete the hack, to be done when other mods have updated
-function mesecon.receptor_on(self, pos, rules)
-	if (self.receptor_on) then
-		print("[Mesecons] Warning: A mod with mesecon support called mesecon:receptor_on.")
-		print("[Mesecons]          If you are the programmer of this mod, please update it ")
-		print("[Mesecons]          to use mesecon.receptor_on instead. mesecon:* is deprecated")
-		print("[Mesecons]          Otherwise, please make sure you're running the latest version")
-		print("[Mesecons]          of that mod and inform the mod creator.")
-	else
-		rules = pos
-		pos = self
-	end
-	mesecon.queue:add_action(pos, "receptor_on", {rules}, nil, rules)
-end
-
-function mesecon.receptor_off(self, pos, rules)
-	if (self.receptor_off) then
-		print("[Mesecons] Warning: A mod with mesecon support called mesecon:receptor_off.")
-		print("[Mesecons]          If you are the programmer of this mod, please update it ")
-		print("[Mesecons]          to use mesecon.receptor_off instead. mesecon:* is deprecated")
-		print("[Mesecons]          Otherwise, please make sure you're running the latest version")
-		print("[Mesecons]          of that mod and inform the mod creator.")
-	else
-		rules = pos
-		pos = self
-	end
-	mesecon.queue:add_action(pos, "receptor_off", {rules}, nil, rules)
-end
-
 -- Un-forceload any forceloaded mapblocks from older versions of Mesecons which
 -- used forceloading instead of VoxelManipulators.
 local old_forceloaded_blocks = mesecon.file2table("mesecon_forceloaded")