relax SVN archive

Fix for the storing of the N-state model back-calculated RDC and PCS data.

The RDC and PCS Q factors for each alignment is now stored as a dictionary in the relax data store.

Fix for a divide by zero error in the PCS Q factor function.

The RDC and PCS Q factor functions are now more robust when data is missing.

The data checks are now more extensive.

Fixes for the N-state model optimisation for when a subset of tensors are fixed.

The RDC and PCS data was incorrectly assembled.

Updated the N-state model analysis code to handle the per-alignment tensor fixed flag.

This allows subsets of tensors to be optimised while the others are fixed.

Updated the relax data store alignment tensor objects to allow for the per-tensor fixed flag.

Syntax error in the align_tensor.fix user function front end.

Syntax fix in the all_tensors_fixed() function.

Renamed all_fixed() to all_tensors_fixed().