bug#6387: 24.0.50; ESC TAB should be bound to `isearch-complete'

[Drew Adams]

> > In isearch.el, we have this:
> > (define-key map "\M-\t" 'isearch-complete)
> >
> > We should also have this, so `ESC TAB' works too:
> > (define-key map [escape tab] 'isearch-complete)
> 
> I wonder why `ESC C-i' works in isearch, but `ESC TAB' doesn't work.
> (There is no special key binding for `ESC C-i' in isearch.)

See this comment in the code:

    ;; To handle local bindings with meta char prefix keys, define
    ;; another full keymap.  This must be done for any other prefix
    ;; keys as well, one full keymap per char of the prefix key.  It
    ;; would be simpler to disable the global keymap, and/or have a
    ;; default local key binding for any key not otherwise bound.
    (let ((meta-map (make-sparse-keymap)))
      (define-key map (char-to-string meta-prefix-char) meta-map)
      (define-key map [escape] meta-map))
    (define-key map (vector meta-prefix-char t) 'isearch-other-meta-char)