Add technic.register_cable_tier(name, tier) (#294)

Co-authored-by: BuckarooBanzay <BuckarooBanzay@users.noreply.github.com>

technic/doc/api.md

@@ -27,6 +27,10 @@ Helper functions
 	* Tells whether the node `nodename` is the cable of the tier `tier`.
 * `technic.get_cable_tier(nodename)`
 	* Returns the tier of the cable `nodename` or `nil`.
+* `technic.register_cable_tier(nodename, tier)`
+	* Register user defined cable to list of known tier cables.
+	* `nodename`: string, name of the node
+	* `tier`: string, tier name
  * `technic.trace_node_ray(pos, dir, range)`
 	* Returns an iteration function (usable in the for loop) to iterate over the
 	  node positions along the specified ray.

technic/machines/register/cables.lua

@@ -9,6 +9,13 @@ function technic.get_cable_tier(nodename)
 	return cable_tier[nodename]
 end
 
+function technic.register_cable_tier(name, tier)
+	assert(technic.machines[tier], "Tier does not exist")
+	assert(type(name) == "string", "Invalid node name")
+
+	cable_tier[name] = tier
+end
+
 local function item_place_override_node(itemstack, placer, pointed, node)
 	-- Call the default on_place function with a fake itemstack
 	local temp_itemstack = ItemStack(itemstack)