bug#69993: Wrap window buffers while cycling

[martin rudalics]

> So no problem, tab-line.el is the right place since later I could
> also implement drag'n'drop of tabs to allow manually changing
> the order of buffers in the window buffers list.

Your are throwing out the child with the bathwater.  I think your
earlier patches for 'switch-to-prev-buffer' and 'switch-to-next-buffer'
were good.  Just the doc of the option was too tab-line specific.

martin