Merge branch '2876_cleanup'

Merge branch '2876_cleanup'

* 2876_cleanup:
  Update EN and RU man pages: add missing options.
  fixed doxygen documentation
  fixed doxygen.cfg, excluded directory /tests/ from doxygen path's
  removed obsolete params from edit_push_undo_action/edit_push_redo_action
  Ticket #2861: additional error handling in edit_save_block().
  (str_utf8_normalize): ret rid of extra memory allocation.
  Use g_strndup() instead of g_strdup()
  (get_absolute_name): missing finish NULL in vfs_path_append_vpath_new() call.
  (edit_do_undo): cleanup of labeled statement usage.
  Fix mouse event handling in menu that overlaps buttonbar.
  mcdiffview: code cleanup and cosmetics.
  Reorder checks in configure.ac.
  Cleanup of screen library detection m4 code.
  Refactoring of many conditions.
  (edit_do_search): refactoring of search loop condition.
  Avoid double checks of bookmarks in editor.
  Ticket #2876: code cleanup before 4.8.6 release.