relax SVN archive

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.

Created the Pcs.test_pcs_copy_different_spins system test.

This will be used to show a limitation of the pcs.copy user function in that it cannot copy data
between two data pipes with different molecule, residue, and spin sequences.

Small formatting change for the rdc.copy user function printouts.

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

This allows the back-calculated RDCs to be additionally copied together with the real value and
error.

Modified the rdc.copy printout of RDCs to occur for each alignment ID.

Created the Rdc.test_rdc_copy_back_calc system test.

This will be used to implement the back_calc Boolean argument for the rdc.copy user function to
allow not only measured, but also back-calculated RDC values to be copied.

Modified the rdc.copy user function to printout all copied RDC values and errors.