also reduced verbosity for python and fixed the c++ test build settings

notifier.py is now in ipaaca.util

- fixed typo in ipaaca documentation

- made sure the initializer is only initialized once
- toString methods for payload and localIU

- Minor cleanups

A new dedicated MessageConverter was added at the same time.

Important: Java version does not yet contain
  Messages (or Retraction, for that matter)
Note: Messages are received and routed to the
  handlers with the special new MESSAGE event
  type, as opposed to ADDED. This decision is
  of course open for discussion.
Additional bugfix: Typecasting conflict in C++
  payloads fixed. Reverted to cstdlib casts
  to avoid bulky exceptions being thrown.

Important: Java version does not yet contain
  Messages (or Retraction, for that matter)
Note: Messages are received and routed to the
  handlers with the special new MESSAGE event
  type, as opposed to ADDED. This decision is
  of course open for discussion.