2 more steps left: add back-sql directory itself, and update Win32 build environment.

Commit based upon patch and comments provided by Alan Clark <aclark@novell.com>.
> Kudos to Dave Steck for the find and fix

root and client ndns.  (the existing backend protections
*should* be good enough, but one cannot be too safe)

with authentication id and authorization ids.  Note: this routine
doesn't actually negotiate anything.  It likely should be renamed
ldap_sasl_auth_s() or ldap_sasl_bind_multistep() or something.

modules are dynamically loaded, they summon libldap when needed.
However, depending on the security libraries available when the
shared libldap was built, the latter brings up other dependencies.
On some platforms, it seems that no solution is available: no
indirect dynamic dependencies.  But for some platforms where this
is supported (in particular, Linux), the shared libldap must
contain info on what other dynamic libraries it needs.  We were
failing to put this info into the shared library.  This patch
seems to fix it.

except where we should.

Don't use LDAP_OPERATIONS_ERROR for internal errors.  Use LDAP_OTHER
instead.  (more changes needed in this area)

must be specified for each database.

Add comment concerning sequencing issues which need to be resolved
by reworking of connection state machine.  Add note that a race
condition exists until this rework is complete.
Rework extended operations to return pointer to static error text.

non-bind requests while a multi-step SASL bind process
is under to connection.c.  Return LDAP_OPERATIONS_ERROR,
not LDAP_SASL_BIND_IN_PROGRESS.

notice to bottom of document.  Reformat paragraph.  Separate
trademark statement from terms.  This edit do not change the
licensing terms.

Only return SLAPD_DISCONNECT with a send_ldap_disconnect()
was called.
Add initial code for support predetermined filter results
when filter is undefined (or known to be true or false).

limited subtype support, modlist handling, filter updates,
lastmod attribute handling.

impl of slap_modlist2mods() and is_at_subtype().