nicer error handling
cmstart -> cmcontinue in random file queries
revamp MorebitsDotNet, make Commons login work again

- keep a whole CookieContainer, instead of storing only selected cookies
- fix a strange bug (first reported 1 May) whereby CentralAuth cookies are
  being stored as if they belong to the domain ".commons.wikimedia.org"
  (note leading period). This means these cookies do not get sent to
  Commons, and the user is not considered logged-in. The "fix" is really a
  bit of a hack, but seems to work.
- plus miscellaneous stuff
updates for 1.0.5.10