arena corruption.

ldap_modify: delete of last attribute value should delete attribute (ITS#229)
thr_nt: use sleep to yield

Set flags without relying on errno (this change may be gratuitous
or wrong).

Includes support for update referral for each replicated backend.
	Reworked replication test to use update referral.
Includes major rewrite of response encoding codes (result.c).
Includes reworked alias support and eliminates old suffix alias codes
(can be emulated using named alias).
Includes (untested) support for the Manage DSA IT control.
Works in LDAPv2 world.  Still testing in LDAPv3 world.
Added default referral (test009) test.

More error checking and reporting.
Slowly getting there, SSL_accept succeeds now, but connection breaks
immediately after that (my glue logic with slapd is broken).

Change temporarily the default protocol from TLSv1 to SSLv3 with
fallback to SSLv2.  This seems necessary for slapd to accept connections
from Netscape.
Try to set the cipher list in the default context.  Does not semm to
work yet.

Add use of TLS_LIBS so that test tools compile

Add tls.c
Add use of TLS_LIBS so that test tools compile

First version of TLS glue for SSLeay/OpenSSL originally written by
Bart Hartgers.  Untested.

Add digest md5 codes to -lldap/-lldap_r (work in progress)

Make sure the token_val argument to get_token is always initialized
to something, either newly allocated memory or NULL.