Add a conformance table in the README

We should investigate the current state of the tools one by one
and mark out those that are complete and POSIX conformant.

README

@@ -6,82 +6,162 @@ across UNIX and UNIX-like systems.
 
 The following programs are currently implemented:
 
-basename
++---------+-----------+--------+
-cal
+|UTILITY  |POSIX      |FEATURES|
-cat
+|         |CONFORMANCE|MISSING |
-chgrp
++---------+-----------+--------+
-chmod
+|basename |           |        |
-chown
++---------+-----------+--------+
-chroot
+|cal      |           |        |
-cksum
++---------+-----------+--------+
-cmp
+|cat      |           |        |
-col
++---------+-----------+--------+
-cols
+|chgrp    |           |        |
-comm
++---------+-----------+--------+
-cp
+|chmod    |           |        |
-csplit
++---------+-----------+--------+
-cut
+|chown    |           |        |
-date
++---------+-----------+--------+
-dirname
+|chroot   |           |        |
-du
++---------+-----------+--------+
-echo
+|cksum    |           |        |
-env
++---------+-----------+--------+
-expand
+|cmp      |           |        |
-expr
++---------+-----------+--------+
-false
+|col      |           |        |
-fold
++---------+-----------+--------+
-grep
+|cols     |           |        |
-head
++---------+-----------+--------+
-hostname
+|comm     |           |        |
-kill
++---------+-----------+--------+
-link
+|cp       |           |        |
-ln
++---------+-----------+--------+
-logname
+|csplit   |           |        |
-ls
++---------+-----------+--------+
-md5sum
+|cut      |           |        |
-mkdir
++---------+-----------+--------+
-mkfifo
+|date     |           |        |
-mktemp
++---------+-----------+--------+
-mv
+|dirname  |           |        |
-nice
++---------+-----------+--------+
-nl
+|du       |           |        |
-nohup
++---------+-----------+--------+
-paste
+|echo     |           |        |
-printenv
++---------+-----------+--------+
-printf
+|env      |           |        |
-pwd
++---------+-----------+--------+
-readlink
+|expand   |           |        |
-renice
++---------+-----------+--------+
-rm
+|expr     |           |        |
-rmdir
++---------+-----------+--------+
-sleep
+|false    |           |        |
-setsid
++---------+-----------+--------+
-sort
+|fold     |           |        |
-split
++---------+-----------+--------+
-sponge
+|grep     |           |        |
-strings
++---------+-----------+--------+
-sync
+|head     |           |        |
-tail
++---------+-----------+--------+
-tar
+|hostname |           |        |
-tee
++---------+-----------+--------+
-test
+|kill     |           |        |
-touch
++---------+-----------+--------+
-tr
+|link     |           |        |
-true
++---------+-----------+--------+
-tty
+|ln       |           |        |
-uudecode
++---------+-----------+--------+
-uuencode
+|logname  |           |        |
-uname
++---------+-----------+--------+
-unexpand
+|ls       |           |        |
-uniq
++---------+-----------+--------+
-unlink
+|md5sum   |           |        |
-seq
++---------+-----------+--------+
-sha1sum
+|mkdir    |           |        |
-sha256sum
++---------+-----------+--------+
-sha512sum
+|mkfifo   |           |        |
-wc
++---------+-----------+--------+
-xargs
+|mktemp   |           |        |
-yes
++---------+-----------+--------+
+|mv       |           |        |
++---------+-----------+--------+
+|nice     |           |        |
++---------+-----------+--------+
+|nl       |           |        |
++---------+-----------+--------+
+|nohup    |           |        |
++---------+-----------+--------+
+|paste    |           |        |
++---------+-----------+--------+
+|printenv |           |        |
++---------+-----------+--------+
+|printf   |           |        |
++---------+-----------+--------+
+|pwd      |           |        |
++---------+-----------+--------+
+|readlink |           |        |
++---------+-----------+--------+
+|renice   |           |        |
++---------+-----------+--------+
+|rm       |           |        |
++---------+-----------+--------+
+|rmdir    |           |        |
++---------+-----------+--------+
+|sleep    |           |        |
++---------+-----------+--------+
+|setsid   |           |        |
++---------+-----------+--------+
+|sort     |           |        |
++---------+-----------+--------+
+|split    |           |        |
++---------+-----------+--------+
+|sponge   |           |        |
++---------+-----------+--------+
+|strings  |           |        |
++---------+-----------+--------+
+|sync     |           |        |
++---------+-----------+--------+
+|tail     |           |        |
++---------+-----------+--------+
+|tar      |           |        |
++---------+-----------+--------+
+|tee      |           |        |
++---------+-----------+--------+
+|test     |           |        |
++---------+-----------+--------+
+|touch    |           |        |
++---------+-----------+--------+
+|tr       |           |        |
++---------+-----------+--------+
+|true     |           |        |
++---------+-----------+--------+
+|tty      |           |        |
++---------+-----------+--------+
+|uudecode |           |        |
++---------+-----------+--------+
+|uuencode |           |        |
++---------+-----------+--------+
+|uname    |           |        |
++---------+-----------+--------+
+|unexpand |           |        |
++---------+-----------+--------+
+|uniq     |           |        |
++---------+-----------+--------+
+|unlink   |           |        |
++---------+-----------+--------+
+|seq      |           |        |
++---------+-----------+--------+
+|sha1sum  |           |        |
++---------+-----------+--------+
+|sha256sum|           |        |
++---------+-----------+--------+
+|sha512sum|           |        |
++---------+-----------+--------+
+|wc       |           |        |
++---------+-----------+--------+
+|xargs    |           |        |
++---------+-----------+--------+
+|yes      |           |        |
++---------+-----------+--------+
 
 The  complement of  sbase  is  ubase[1] which  is  Linux-specific  and
 provides all  the non-portable tools.   Together they are  intended to