Re: isearch multiple buffers

[Richard Stallman]

isearch-multi.el seems like a better name for the new file.

    Also I implemented a new minor mode isearch-buffers-minor-mode
    that sets a group of variables necessary for this feature.
    Turning off this minor mode deletes all created buffer-local bindings.
    So any major mode that uses this feature can simply set the variable
    isearch-buffers-next-buffer-function and call isearch-buffers-minor-mode.

To make this a minor mode is undesirable because we do not want users
to enable and disable it.  I think it should simply be a subroution
for that major modes can call.

    !       (if (and (boundp 'isearch-buffers-next-buffer-function)
    !          isearch-buffers-next-buffer-function
    !          (boundp 'isearch-buffers-current-buffer)

Why test boundp of these variables.  Isn't it better to have them
always always bound, and just test for non-nil?