Add a -v flag for ls which sorts entries following a natural ordering using strverscmp(3) (e.g. "bloem1 bloem9 bloem10" as opposed to "bloem1 bloem10 bloem9"). Update the manual page and add a test case. Reviewed by: pauamma, bcr Tested by: pstef Differential Revision: https://reviews.freebsd.org/D36407