(goto-history-element): New function created from

(goto-history-element): New function created from
next-history-element.
(next-history-element): Most code moved to goto-history-element.
Call goto-history-element with (- minibuffer-history-position n).
(previous-history-element): Call goto-history-element with (+
minibuffer-history-position n).
(minibuffer-setup-hook): Add minibuffer-history-isearch-setup.
(minibuffer-history-isearch-message-overlay): New buffer-local variable.
(minibuffer-history-isearch-setup, minibuffer-history-isearch-end)
(minibuffer-history-isearch-search, minibuffer-history-isearch-message)
(minibuffer-history-isearch-wrap, minibuffer-history-isearch-push-state)
(minibuffer-history-isearch-pop-state): New functions.