rapid overhaul

engine now tracks threads by a class record TerminalProcess() for brevity

'reply' now quotes text, sorts by thread, added can_tag ACL.

added 'tap_events' option, default to 'no', removes sensative
chat & etc. broadcasts when debug is enabled.

added 'max_depth' option, default to 8, specifies maximum search
recursion depth for parent/child relationships

made incremental improvements to bbs lister, esp. in regards to refresh, still bugs to kink ..
fixes for private messaging