Backend documentation patch, version 1

================
Most of this text is taken from OpenLDAP.  The work of rewriting it
to manual pages is done by by Hallvard B. Furuseth and placed into
the public domain.  This software is not subject to any license of
the University of Oslo.
================

Hallvard B. Furuseth <h.b.furuseth@usit.uio.no>, April 2002.

ucdata-path, moduleload, modulepath. sasl-external-x509dn-convert has
been deleted from the code.

without NEW_LOGGING. Added logfile.

ITS#1677 - cast away const warnings
ITS#1678 - unsigned char args to ctype funcs
ITS#1682 - don't redefine ldap_debug
ITS#1683 - uninitialized vars
ITS#1703 - ldo_debug initialization
ITS#1705 - unsigned testing
ITS#1706 - socklen_t args
ITS#1719 - back-tcl update (other cleanups/fixes/improvements; yet untested)
ITS#1724 - integerNormalize/integerFilter/integerIndexer bugs
ITS#1725 - libdes not required

Implement back-null (/dev/null style backend)
Cleanup some misc warnings ("%lu" format, unused/uninitialized vars,
        ambiguous operator precedence)

Kurt, please regenerate configure

Add shtool use to TODO list