* Remove documentation of how krlogind gets its command line options

* Remove documentation of how krlogind gets its command line options
from its name, because it doesn't any more.  Same for kshd.

* Document and implement -i option to ignore checksums.  Restore
default mode to accept and process checksums if provided.

* Bring back the warning about only using -c with Kerberos5.  The
documentation (both install.texi and the man pages) clearly state that
the -c option shouldnot be used in conjunction with Kerberos4, so warn
users if they try.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@7849 dc483132-0cff-0310-8789-dd5450dbe970