[Seaside] breadcrumbs

[Avi Bryant]

I've just committed a new (Monticello based) snapshot of Seaside at
http://beta4.com/mc/seaside/Seaside2-ab.2.mcz .

This includes an example of a breadcrumbs trail (of the kind I was
calling "nested", ie, following site hierarchy not workflow steps) as part
of the WAStore example.

To see it in action, go to /seaside/store.

To see the implementation, look at WATrail.  This works in the following
way: you construct it by giving it the root/home component (WATrail on:
home).  It will display a path of the series of any nested delegates (that
is, the component you #call: from home, then the component you call from
that component, etc), that respond to #trailName.  #trailName should
return a string that will be used to identify that item in the breadcrumb
trail.

When you click on an item in the trail, that component's delegate will be
cleared, which means that the user will be brought back to that point.
This is a generalization of the #clearDelegate approach to the Home link
that I first suggested to Todd.

If this is fuzzy to people, try it out.  If it's still fuzzy, I'll explain
further... ;)

Avi