Add debug messages for configuration parser.
Change initial verbosity of the logfile logger to DEBUG.

Otherwise, all debug messages created before proper file logging is set
up would be ignored.

Problem: You now ALWAYS get all debug messages, regardless of the
specified loglevel in the configuration file. Maybe there is some option
to remove all messages below a certain level before flushing the
MemoryHandler into the FileHandler? But good for now, as debug output in
the logfile is desired behaviour.