Update Popwin package and setup

* Update of the `popwin.el` package.
* Define another `popwin:popup-window-height`, default of `15` is to low. (for example for `rgrep` and `compilation` buffer)
* Set `special-display-function` variable to `popwin:display-buffer`.
  Reason:

  > `popwin:display-buffer` displays special buffers in a popup window
  > and displays normal buffers as unsual. Special buffers are
  > specified in `popwin:special-display-config`, which tells popwin
  > how to display such buffers. See docstring of
  > `popwin:special-display-config` for more information.