Merge branch '4490_cleanup'

Merge branch '4490_cleanup'

* 4490_cleanup: (31 commits)
  Update po/*.po files.
  ext.d/image.sh: use exiftool in addition to exif to view image metadata.
  ext.d/image.sh: check $DISPLAY in the xpm View action.
  mc.ext.ini: support avif images.
  mc.ext.ini: add View action for webp images.
  Update copyright years.
  (main): call tty_check_term() right after mc_args_parse().
  Refactor learn keys.
  Use g_string_new_take().
  (test_glob_prepare_replace_str): remove unneeded type cast.
  maint/utils/update-years.sh: replaced unportable 'sed -i' command.
  maint/utils/update-years.sh: add src/man2hlp/man2hlp.in.
  src/man2hlp/man2hlp.in: collapse copyright years.
  (str_utf8_offset_to_pos): change type of variable.
  (mc_search_regex__get_max_num_of_replace_tokens): refactor loop.
  lib/widget/input_complete.c: remove intermediate variables.
  mcedit: add intermediate variables to make code more readable and debuggable.
  (is_blank): refactor loop.
  (edit_help): use help node of editor dialog.
  (tree_execute_cmd): move CK_Help handler to separate function tree_help()
  ...