Existing D6 code was partially wrong already.  Tried to limit the fixes to new code as much as possible.

#308858 by smk-ka: Fixed user sessions sometimes not properly created in vBulletin due to a different vB behavior upon user login.

#308860 by smk-ka: Added separate login/logout menu handlers to accommodate different session lifetimes.

#308857 by smk-ka: Fixed usernames containing non-latin1 characters not synced due to missing encoding.

by smk-ka, sun: Added block and Panels content-type for displaying recent user posts.
#252677 by smk-ka, sun: Fixed wrong mapping for existing vB users after logon in Drupal.
#128322 by smk-ka, sun: Code clean-up.

#131877 by sun: Fixed warning messages if config.php could not be found.
#119327 by sun: Fixed wrong forum path due to missing database access.
#130048 by sun: Fixed fatal error on mysqli by implementing new database interface.
#119334 by sun: Fixed SQL errors due to wrong db_url.
#114718 by sun: Fixed table not found error due to wrong table prefix.