relax SVN archive

Converted the spin RDC and PCS data structures to dictionaries using align_id as a key.

This is a big structural update which solves many problems with incomplete data.

Added calls to rdc.display() and pcs.display() to the lactose N-state model system test.

This adds more checks for these user functions.

Removal of a few unused imports.

Docstring fix for the read() function.

This is the PCS, not RDC.

Fix for the RDC and PCS display() and write() user functions for when no errors exist.

Added a call to pcs.display() in the DNA PCS system test.

This is to test out the operation of this user function.

Clean up of the RDC and PCS modules.

All the residual code from the relax_data module has been eliminated.

Added 2 system tests for alignment tensor optimisation using DNA PCS data.

Wrote the back end for the pcs.display() and pcs.write() user functions.

Wrote the back end for the rdc.display() and rdc.write() user functions.