vimrc: handle alt window in Windo

Source: https://github.com/Konfekt/FastFold/pull/10
Update submodule oh-my-zsh 98f0f49...2ef4b40

* oh-my-zsh 98f0f49...2ef4b40 (4):
  > Remove zlogin; copied from dotfiles upstream, not used
  > Reduce diff to robbyrussell/master
  > Merge remote-tracking branch 'upstream/master'
  > preexec: fix CMD detection for '=cmd foo'