Made links not be underlined, as the TOC becomes very cluttered and unreadable. Clickable URLs are still obvious though, so not much difference.

Changed Makefile to use htmldoc bach mode and created a guide.book file with htmldoc nice GUI config tool. We now have an OpenLDAP logo on the front of the PDF, plus other cool touches. Please test.

- support for the privateDB control, which allows regular LDAP operations
  to address the private database instead of the proxied one.
  This is essentially intended for cache monitoring and maintenance
- support for the queryDelete extended operation, which allows to delete
  from the cache database either a cached query, specified by queryId,
  or all queries related to a specific cached entry, specified by entryDN