relax SVN archive

Converted generic_fns.relax_data.copy() to the new relax design.

Fixed the checking of the pipe_from and pipe_to args in the relax_data.copy() user function.

Added a new arg unit test for the relax_data.copy() user function, checking when both pipes are None.

Brought the relax_data.copy() user function arg unit tests into line with the other copy() functions.

Fix for indecies in the test_copy_protein_sequence() unit test.

Missing deepcopy import.

Modified exists_mol_res_spin_data() to accept the data pipe arg.

Wrote the sequence.copy() user function.

Wrote the generic_fns.sequence.copy() function.

Wrote 3 arg unit tests for the sequence.copy() user function.