relax SVN archive

Another attempt at fixing a nasty circular import in the relax GUI.

Added data pipe bundle error checking for the GUI pipe editor window associate_auto() method.

Added some error checking for the data pipe bundle in the auto model-free analysis GUI code.

Missing import of the sys module.

Added some special RelaxErrors for data pipe bundles.

Added some bug catching code for the observer objects.

In some rare cases a registered method's key was set to None. This is now caught and a RelaxError
thrown to prevent later indecipherable errors.

The setup.py application building script now complains if the Python setuptools are not installed.

Import fix for the relax GUI tests for a problem only recently introduced.

Fix for the relax user manual compilation.

The full path for an icon in the graphics directory was being used.

Updated the relax prompt mode figure in the intro chapter of the user manual to the more modern prompt.