the markmessageinterval was not correctly propagated to all places
where it was needed. This resulted in rsyslog using the default
(20 minutes) in some code pathes, what looked to the user like mark
messages were never written.

- moved module loader from conf.c to module.c, where it belongs
- made the necessary plumbing to auto-load library modules
- upgraded debug system to include iRet in function exit message
- changed module interface so that instances need only to be supported by
    output plugins (if we actually need them for input plugins, we can
    always add it again...)
- milestone: first implementation of library modules (but do not get
    unloaded on exit/hup so far)

- changed module interface version, as the interface change is quite large

- implemented management function for worker thread 0 in order to change
    queue workers dynamically -- stage work

    was specified in rsyslog.conf
- fixed a bug that caused a segfault on queues with types other than "disk"
- removed the now longer needed thread TermSyncTool

    See newsgroup posting for details on the issue:
    http://groups.google.com/group/comp.programming.threads/msg/330b9675f17
    a1ad6 I tried some mutex operations but came to the conclusion that
    this does not really help. So I have now switched to plain thread
    cancellation, which so far seems to be OK. Need more practical
    experience with other input modules to make a final decision. Thus I
    leave all code in and have just disabled the problematic code.