relax SVN archive

Modified the N_state_model.test_data_copying system test to skip deselected spins.

The pcs.copy user function now skips deselected spins.

Fix for the pcs.copy user function for a recently introduced problem (r27747).

The data pipe for the spin_loop() function must be supplied.

Fixes for the Pcs.test_pcs_copy_different_spins and Pcs.test_pcs_copy_back_calc system tests.

Modified the pcs.copy user function to handle different spin sequence between data pipes.

Added full per-alignment data printouts to the pcs.copy user function to match rdc.copy.

The feedback is important to know what was actually copied.

Implemented the back_calc argument for the pcs.copy user function.

This allows the back-calculated PCSs to be additionally copied together with the real value and
error. The implementation simply copies that of the rdc.copy user function.

Created the Pcs.test_pcs_copy_back_calc system test.

This will be used to implement the back_calc Boolean argument for the pcs.copy user function to
allow not only measured, but also back-calculated PCS values to be copied. It matches the
equivalent Rdc.test_rdc_copy_back_calc system test.

Added a printout of the alignment ID for the pcs.copy user function.

This is to match the rdc.copy user function.

Fix for the pcs.read user function.

The problem was caught by the new Pcs.test_pcs_copy_different_spins system test. If the spin system
does not exist in the current data pipe, but data for it is present in the PCS file, the pcs.read
user function would terminate in a TypeError.