relax SVN archive

Large code refactorisation - the current data pipe is now in __builtin__.cdp.

The result is the removal of 484 calls to generic_fns.pipes.get_pipe() to get the current data pipe.

Added a system test for the frame order 'rigid' model with no tensor rotations and no motion.

Added a missing alias for the current data pipe.

Rearrangement of the handling of frame order models.

The tensor rotation Euler angles are now model independent, the 'rigid' model is better supported,
and a clear isolation of the isotropic cone model has been made.

Added __description__ strings to the user function class relax help strings.

The __strip_lead() method has been added to User_fn_class to remove leading whitespace from the
__description__ strings.

Changed a flag to a bool type.

Fix for the turning off of minimisation constraints.

The algorithm needs to also change.

Bug fix for the ref_domain() method.

This method now works if no domain names have been associated with the tensors.

Constraints are now automatically turned off, if the minimisation option is set to True.

These are not yet implemented!

Created the 'rigid' frame order model.