relax SVN archive

Bug fix for the setup of the N-state model target function.

This is triggered by missing data.

Created the test_metal_pos_opt() N-state model system test.

Specific RDC and PCS data for this test has also been generated.

Created a system test script for checking one type of algorithm for Ln3+ position optimisation.

Another fix for a recent bug in _minimise_bc_data().

Fix for the N-state model _minimise_bc_data() method for when no alignments are present.

This fixes a recently introduced problem.

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.