first round of s/sprintf/snprintf/; the rationale is: truncate error messages rather than buffer overflow; otherwise, assert that no buffer overflow occurred.  In some cases, error handling could be added.

needed.

- 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

Also make remove_query_and_data() return void (it returned nothing) and
remove an unused variable.

fix error checking when parsing UUID (detected by Coverity); added check/prettification of UUID, just in case...

(ConfigReply) for the error messages.

_db_destroy functions.