cta::exception::NoPortInRange

Renamed CTA/tapeserver/castor to CTA/tapeserver/castor_checkout in preparation for the moving the sub-directory CTA/tapeserver/castor/castor up the directory tree

Fixed h/rfcntl.h which missed multiple inclusion guards entirely.

Added an std::exception::Backtrace class, providing a backtrace attached to all exception.
Fixed minor side effects (virtual destructors, catch orders) induced by the inheritance from std::exception.

Another major cleanup of the castor code targetting to drop all warnings due to the -Wextra flag. On the way, many little bugs were fixed (possible core dumps in command lines, wrong or missing checks, ...), code was dropped since unused, files were converted from dos to unix end of line convention, etc, etc ...