Port message handling to fmatvec::Atom

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The fmatvec::Atom class provided now a general message handling functionallity. 
All MBSim code should be switched to this:

Details:
- Derive all MBSim classes from fmatvec::Atom (if not already done)
- Replace all occurence of std::cout<<... and std::cerr<<... by
  msg(Info)<<... or msg(Warn)<<...
- Maybe add more message types to fmatvec::Atom e.g. "Progress" for the
  time prints; "Warn2" for higher warning levels; ...
- But do not add a "Error" message type since errors should stop the
  simulation and hence throw MBSimError instead of printing messages
- Remove all DEBUGLEVEL, warnLevel, ... variables in MBSim and replace these
  by proper msgAct(<MessageLevel) calles.

Original issue reported on code.google.com by friedrich.at.gc@googlemail.com on 21 Jun 2014 at 3:55