relax SVN archive

The idea of this system was suggested in two threads which commence at:
https://mail.gna.org/public/relax-devel/2006-08/msg00052.html
https://mail.gna.org/public/relax-devel/2006-08/msg00053.html

The improvements includes the addition of the printing of the traceback, the option of saving the
program state (self.relax.data pickling), a new way of calling the RelaxErrors or RelaxWarnings
(for example RelaxBadError('Hello')), addition of the warning functions, and a number of other small
changes.