Support utf8 on the wire for ads ldap. DN's are converted, as well as strings,

Support utf8 on the wire for ads ldap.  DN's are converted, as well as strings,
though it is up to the calling function to decide whether values are
strings or not.  Attributes are not converted at this point, though support
for it would be simple.

I have tested it with users and groups using non-ascii chars, and if the
check for alphanumeric user/domain names is removed form sesssetup.c, even
a user with accented chars can connect, or even login (via winbind).

I have also simplified the interfaces to ads_mod_*, though we will probably
want to expand this by a few functions in the near future.  We just had
too many ways to do the same thing...
(This used to be commit f924cb53580bc081ff34e45abba57629018c68d6)