ls.1:
- Sort options in `SYNOPSIS', the option list, and texts within
the man page;
- improve wording;
- improve macro usage;
- use more consistency regarding (locations for) information about
which options override which;
- cross-reference `-d' and `-R';
- simplify description of `-k', removing redundant and unneeded
information;
- sort entry type list (but leave `-a' and `-A' as they are, given
their meaning);
- correct / augment description of `BLOCKSIZE' environment variable
in `ENVIRONMENT' section;
- bump date.
ls.c:
- Sort options in `usage';
- augment comment about when to figure out block size.