implement Timer.terminate/2 and fix related message

```
warning: Rclex.Timer.terminate_timer/2 is undefined or private. Did you mean one of:

      * terminate/2

  lib/rclex.ex:83: Rclex.waiting_input/2
```

lib/rclex.ex

@@ -80,7 +80,7 @@ defmodule Rclex do
       |> String.to_integer()
 
     case num do
-      0 -> Rclex.Timer.terminate_timer(sv, child)
+      0 -> Rclex.Timer.terminate(sv, child)
       _ -> waiting_input(sv, child)
     end
   end

lib/rclex/sub_loop.ex

@@ -91,12 +91,12 @@ defmodule Rclex.SubLoop do
 
   # def terminate(:normal, state) do
   def terminate(:normal, _) do
-    Logger.debug("loop process killed : normal")
+    Logger.debug("sub_loop process killed : normal")
   end
 
   # def terminate(:shutdown, state) do
   def terminate(:shutdown, _) do
-    Logger.debug("loop process killed : shutdown")
+    Logger.debug("sub_loop process killed : shutdown")
   end
 
   def do_nothing() do

lib/rclex/subscriber.ex

@@ -95,7 +95,7 @@ defmodule Rclex.Subscriber do
   end
 
   def terminate(:normal, _) do
-    Logger.debug("sub terminate")
+    Logger.debug("terminate subscriber")
   end
 
   # defp do_nothing do

lib/rclex/timer.ex

@@ -50,4 +50,8 @@ defmodule Rclex.Timer do
     Supervisor.stop(loop_supervisor_id)
     {:stop, :normal, {callback, args, time, loop_supervisor_id}}
   end
+
+  def terminate(:normal, _) do
+    Logger.debug("terminate timer")
+  end
 end

lib/rclex/timer_loop.ex

@@ -62,6 +62,14 @@ defmodule Rclex.TimerLoop do
     end
   end
 
+  def terminate(:normal, _) do
+    Logger.debug("timer_loop process killed : normal")
+  end
+
+  def terminate(:shutdown, _) do
+    Logger.debug("timer_loop process killed : shutdown")
+  end
+
   def do_nothing() do
   end
 end