成员的完整列表，这些成员属于 neforce::path_tree::scan_options,包括所有继承而来的类成员

custom_filter	neforce::path_tree::scan_options
dirs_only	neforce::path_tree::scan_options
extensions	neforce::path_tree::scan_options
files_only	neforce::path_tree::scan_options
follow_symlinks	neforce::path_tree::scan_options
include_hidden	neforce::path_tree::scan_options
max_depth	neforce::path_tree::scan_options