Add digiline detector tube (#139)

* Add digiline detector tube

The digiline detector tube outputs an itemstring of every stack
that passes through it on the channel specified in its formspec.

* Don't store digiline detector tube's formspec in a temporary local

default_settings.txt

@@ -10,6 +10,7 @@ pipeworks.enable_pipe_devices = true
 pipeworks.enable_redefines = true
 pipeworks.enable_mese_tube = true
 pipeworks.enable_detector_tube = true
+pipeworks.enable_digiline_detector_tube = true
 pipeworks.enable_conductor_tube = true
 pipeworks.enable_accelerator_tube = true
 pipeworks.enable_crossing_tube = true

signal_tubes.lua

@@ -67,6 +67,55 @@ if pipeworks.enable_detector_tube then
 	})
 end
 
+if minetest.get_modpath("digilines") and pipeworks.enable_digiline_detector_tube then
+	pipeworks.register_tube("pipeworks:digiline_detector_tube", {
+			description = "Digiline Detecting Pneumatic Tube Segment",
+			inventory_image = "pipeworks_digiline_detector_tube_inv.png",
+			plain = { "pipeworks_digiline_detector_tube_plain.png" },
+			node_def = {
+				tube = {can_go = function(pos, node, velocity, stack)
+						local meta = minetest.get_meta(pos)
+
+						local setchan = meta:get_string("channel")
+
+						digiline:receptor_send(pos, digiline.rules.default, setchan, stack:to_string())
+
+						return pipeworks.notvel(pipeworks.meseadjlist, velocity)
+					end},
+				on_construct = function(pos)
+					local meta = minetest.get_meta(pos)
+					meta:set_string("formspec",
+						"size[8.6,2.2]"..
+						"field[0.6,0.6;8,1;channel;Channel:;${channel}]"..
+						"image[0.3,1.3;1,1;pipeworks_digiline_detector_tube_inv.png]"..
+						"label[1.6,1.2;Digiline Detecting Tube]"
+					)
+				end,
+				on_receive_fields = function(pos, formname, fields, sender)
+					if fields.channel then
+						minetest.get_meta(pos):set_string("channel", fields.channel)
+					end
+				end,
+				groups = {},
+				digiline = {
+					receptor = {},
+					effector = {
+						action = function(pos,node,channel,msg) end
+					}
+				},
+			},
+	})
+
+	minetest.register_craft( {
+		output = "pipeworks:digiline_detector_tube_1 2",
+		recipe = {
+			{ "homedecor:plastic_sheeting", "homedecor:plastic_sheeting", "homedecor:plastic_sheeting" },
+			{ "digilines:wire_std_00000000", "mesecons_materials:silicon", "digilines:wire_std_00000000" },
+			{ "homedecor:plastic_sheeting", "homedecor:plastic_sheeting", "homedecor:plastic_sheeting" }
+		},
+	})
+end
+
 if pipeworks.enable_conductor_tube then
 	pipeworks.register_tube("pipeworks:conductor_tube_off", {
 			description = "Conducting Pneumatic Tube Segment",