bug#15200: isearch-other-meta-char and shift

[Stefan Monnier]

> Another problem is that shifted cursor motion keys
> don't activate the region.  Test case:

These are all the kinds of problems one gets into when one reads events
and then want to re-read them in a different context.

My hope is that these kinds of problems would all disappear if we
re-implemented isearch using set-temporary-overlay-map, which would save
us from having to re-read events.


        Stefan