Rename the krb5int_buf_ family of functions to use the k5_ prefix for
brevity.  Reformat some k5buf implementation code to match current
practices.

Mostly this gets rid of the trailing space on line 2 after
bb76891f5386526bdf91bc790c614fc9296cb5fa.

Since there is no overlap between the clpreauth and kdcpreauth
interface declarations, there's no particular reason to combine them
into one header.  For backward compatibility and convenience, leave
behind a preauth_plugin.h which includes both.

Previously, we would happily accept -i or -t name and do nothing
with it, if -k was not given.  If the user is passing -i or -t, they
clearly want to use a keytab, so do so (but print a warning).

While here, enforce that only one of -t and -i is given.

ticket: 7218
tags: pullup
target_version: 1.11

The old man pages are gone, so we can't install them anymore.
Also clean up install and install-unix targets that were installing
the old man pages by hand.

Add a krb5_get_init_creds_opt_set_in_ccache() function.  An input
ccache may hold configuration data which the client libraries can
use to influence their decisions.

ticket: 7413 (new)

We generate man pages from RST sources now; they are checked into
the tree in src/man/.

The gen-manpages directory is no longer needed.

This simply adds KADM5_API_VERSION_4 and various fields to the
policy structures:

 - attributes         (policy-ish principal attributes)
 - max_life           (max ticket life)
 - max_renewable_life (max ticket renewable life)
 - allowed_keysalts   (allowed key/salt types)
 - TL data            (future policy extensions)

Of these only allowed_keysalts is currently implemented.

Some refactoring of TL data handling is also done.

ticket: 7223 (new)