relax SVN archive

Added a dummy overfit_deselect() method to the base class.

This method does nothing.

Updated the base class method sim_return_selected() to the new relax design.

Updated the return_data() and return_error() base class methods to the new relax design.

Updated the base class method has_errors() to the new relax design.

Removed an orphaned comment.

Removed the empty __init__() method and shifted its docstring to that of the class.

Removed the empty __init__() method and shifted its docstring to that of the class.

Alphabetical sorting of the class methods.

Additions to the system test of the 5-state model in the xz-plane (no pivotting of alpha).

The 5-state model is now set up in the script.

Added the missing import of RelaxIntError.