xfwm: support for 2d pagers

[Paramjit Oberoi]

> Paramjit Oberoi wrote:
> >>Committed, but the patch was missing some important parts regarding the
> >>"sidewalk" management.
>
> Introducing the "wrap_layout" option misses scrolling via the scroll 
> wheel. I'll send a patch to correct that.

It is not clear what, if any, changes are required to scroll wheel
scrolling.

Scroll wheel scrolling essentially maps the change-to-next-workspace and
change-to-prev-workspace actions to the scroll wheel.  None of those
actions is directly affected by the wrap_layout option.  It has been
suggested that these actions are obsolete now that 2d navigation has
been implemented...  but even if that is true, what new actions should
scroll wheel scrolling be mapped to?

-param