Log Message:
less: Update to 551

pkgsrc changes:
 - Adjust regexp options to better match the underlaying configure semantic
   by introducing a `regex' group and having `pcre' and `regexp' as possible
   options.
 - Update LICENSE to reflect the licenses really used
 - Take MAINTAINERship

Changes:
Major changes between "less" versions 530 and 551
 * Add --mouse option.
 * Add --wheel-lines option.
 * Add --no-histdups option.
 * Add --save-marks option.
 * Support PCRE2 regular expression library.
 * Redraw screen on SIGWINCH even if screen size doesn't change.
 * Shell-escape filenames in history so they can be used again.
 * Ring bell if user enters invalid long option name.
 * Use PCRE_UTF8 flag for pcre regular expressions when in UTF-8 mode.
 * Windows: use wide-char string to set console title.
 * Don't count lines in initial screen if using -X with -F.
 * Support mingw build system.
 * Fix bug in v command on empty file.
 * Fix bug in v command when filename contains shell metacharacters.