(isearch-mode-map): Bind C-M-w to isearch-del-char,
C-M-y to isearch-yank-char. Bind M-% to isearch-query-replace,
C-M-% to isearch-query-replace-regexp.
(minibuffer-local-isearch-map): Add arrow key bindings.
Bind C-f to isearch-yank-char-in-minibuffer.
(isearch-forward): Doc fix.
(isearch-edit-string): Doc fix.
(isearch-query-replace, isearch-query-replace-regexp): New funs.
(isearch-del-char): Add optional arg. Set isearch-yank-flag to t.
(isearch-yank-char): Add optional arg.
(isearch-yank-char-in-minibuffer): New fun.