allow host resolution via DNS SRV based on the DN portion of the URI if no host is provided (ITS#4996)

do not try to register custom monitor stuff when subordinate (related to ITS#4965); note: this might not be the best solution, because it does not allow to monitor subordinate databases; however, right now it's necessary, since subodinate databases do not register themselves in back-monitor

Started converting images to dia, with a new src folder, and started merging of Wiki docs/info into main guide.

Tighten loop in pool_pause(): Omit unneeded ltp_pcond signals since rev 1.64.
Fix comment.

make searches expand all matching sets of group/url[/member] configurations; relax configuration test as per ITS#4989

Not needed after ldap_int_thread_userctx_t.ltu_id was added and
_pool_wrapper took care not to update thread_keys[] during pauses.
Fix bogus thread_keys[].ctx comment.