Subject: bug#54017: add regexp translation option to read-regexp

From: emacsq <[email-masked]>
Date: Tue, 15 Feb 2022 20:21:35 +0000

Suppose, the user wants to use ( ) for capturing and
\( \) for matching parens. He provides a function
which does this translation.

If this new option is set and is a function which does
the translation then read-regexp will

- accept the format which the user prefers, in this case
( ... ) for capturing.

- store regexps in this format in history, so the user
can work with the user's preferred format even when
retrieving history entries.

- return the elisp format regexp by calling the function
provided by the user which does the translation.