A QT version of the StelFileMgr is in progress.  Shouldn't take too long.  I
will not commit anything until we all agree for sure (I am Ok with the QT

I am done with the mutex stuff. I now use QMutex and QThread. I commit now.

Maybe we should make a SVN tag to mark the last revision of code which is
possible to build without QT?

It's tagged under the name last-without-qt.