Rename/refactor a bunch of cuttlefish settings.

* Update a bunch of docstrings.
* Added 'log.crash' setting which can disable the crash log.
* log.crash.msg_size -> log.crash.maximum_message_size
* log.crash.date -> log.crash.rotation
* log.crash.count -> log.crash.rotation.keep (also made 'current' a
  possible option, which is equivalent with 0)
* Made log.error.redirect and log.error.messages_per_second advanced
  settings