Change. `uv.defer` add max depth level.

```Lua
local timer = uv.timer():start(10000,10000, function()print("hello") end)

sock:bind("*", 5555, {}, function(...)
  -- we are in defer call

  -- this is invalid call but with single level we can no call this callback
  -- so we have to wait `timer` callback or run defer proceed again.
  sock:bind("*", 5556, function(...)
    print("2:", ...)
  end)
end)
```

I do not use internal timer handle because
 * It may need some changes to support lluv.handles() do not list it.
 * I do not think that lluv itself need more than 3-5 level.
 * end user could use `lluv.utils.DeferQueue` by self.