mysql: check for status error

+ I have found cases where an entry isn't removed from
  the wikitrust_queue table.  But when you look at the
  debugging output, the code clearly ran without throwing
  an exception.  Looking over the Mysql docs, it appears that
  errors can happen without throwing an exception, so I added
  some extra checking.
downloadwp2xml: timestamp format was wrong
dispatcher: push 'processing' pages back onto queue
WikiTrustAPI: support JSON-p
wikitrust api: added 'wikimarkup' json method
wpapi: on page_title changes, just update db, not redownload
onlinedb: cleanup of dead function
onlinedb: fixed swapped args to sql statement
wpapi: handle "counter" field being empty
wpapi: also check for parsing errors on revision info
Added sql code in test-data/database-schema.sql to create database schema.
dispatcher: only sleep when there's no work
dispatcher: do some profiling

+ after a few days, our processing queue starts to fill up.
  I find that if I stop the dispatcher and restart, then it empties
  out and keeps up with the load.  This suggests that there is some
  kind of slowdown in the code after some amount of time.
  When I monitor via top, the dispatchers are holding steady around
  205MB memory -- so not a memory leak causing excessive swapping.
dispatcher: don't profile mysql any more
dispatcher: don't profile mysql any more
profile: added monitoring to track CPU overflow
db: nested transactions not allowed; changed weird notation
debug: tracking down slowdown in code
dispatcher: refresh db handles periodically
online_db: use a single SQL update, rather than one for every page