Add support for sorting with the file metadata change time (ctime)

[kamenchunathan]

Add a sorting option for sorting files based on when file metadata last changed / inode change in linux. e.g. when a file was last moved or renamed on disk instead of when file contents changed
This corresponds to the -c option in GNU ls

[eras]

With almost the same effort support for -u for sorting by access time could be implemented. Perhaps the issue title could be changed to include that cas as well?