Add technic_on_disable callback (#592)

This adds a new callback to trigger when the machine is no longer powered by the technic power grid. Also allows mods to override the infotext if needed.

technic/doc/api.md

@@ -136,10 +136,15 @@ Additional definition fields:
 	* Specifies how the tool wear level is handled. Available modes:
 		* `"mechanical_wear"`: represents physical damage
 		* `"technic_RE_charge"`: represents electrical charge
-* `<itemdef>.technic_run(pos, node)`
+* `<itemdef>.technic_run = function(pos, node) ...`
-	* This function is currently used to update the node.
+	* This callback is used to update the node.
 	  Modders have to manually change the information about supply etc. in the
 	  node metadata.
+* `<itemdef>.technic_disabled_machine_name = "string"`
+	* Specifies the machine's node name to use when it's not connected connected to a network
+* `<itemdef>.technic_on_disable = function(pos, node) ...`
+	* This callback is run when the machine is no longer connected to a technic-powered network.
+
 
 ## Node Metadata fields
 Nodes connected to the network will have one or more of these parameters as meta

technic/machines/switching_station.lua

@@ -465,16 +465,17 @@ minetest.register_abm({
 		for tier, machines in pairs(technic.machines) do
 			if machines[node.name] and switching_station_timeout_count(pos, tier) then
 				local nodedef = minetest.registered_nodes[node.name]
-				if nodedef and nodedef.technic_disabled_machine_name then
-					node.name = nodedef.technic_disabled_machine_name
-					minetest.swap_node(pos, node)
-				elseif nodedef and nodedef.technic_on_disable then
-					nodedef.technic_on_disable(pos, node)
-				end
 				if nodedef then
 					local meta = minetest.get_meta(pos)
 					meta:set_string("infotext", S("%s Has No Network"):format(nodedef.description))
 				end
+				if nodedef and nodedef.technic_disabled_machine_name then
+					node.name = nodedef.technic_disabled_machine_name
+					minetest.swap_node(pos, node)
+				end
+				if nodedef and nodedef.technic_on_disable then
+					nodedef.technic_on_disable(pos, node)
+				end
 			end
 		end
 	end,