- Allow lua to chose whatever directories or files can be selected
- Fix selecting directories
- Rename dialog to `guiPathSelectMenu` from `guiFileSelectMenu`
- Rename lua function for opening the menu from `show_file_open_dialog` to `show_path_select_dialog`
- Remove duplicate code and fix code style.
Related changes
- fix `clang-format` whitelist.
- Regenerate minetest.conf.example
