bug#69993: Wrap window buffers while cycling

[martin rudalics]

> Often users complain there is no way to wrap window buffers
> while cycling them with 'C-x C-<left>' (previous-buffer)
> and 'C-x C-<right>' (next-buffer).  One of the latest examples is
> https://old.reddit.com/r/emacs/comments/1barvo2/perwindow_buffer_ordering/
>
> This problem becomes apparent when a list of prev/next window buffers
> is visualized by the tab-line.
>
> So here is the patch that finally solves this problem
> by adding a new option 'switch-to-prev-buffer-wrap'
> disabled by default.
>
> When its value is t, it wraps to the first/last buffer.
> But when the value is 'stop', it stops at the first/last buffer.

Good idea.  You probably should emphasize the point that if this option
is non-nil, the buffer switched to must have appeared in the window
before.

martin