relax SVN archive

Created the generic_fns.pcs module, although nothing will work yet.

Activated the PCS user functions.

Renamed the 'RDC identification string' to the 'alignment identification string'.

Created the interfaces for the PCS user functions.

Spelling fix in the docstrings.

Renamed ave_pcs_tensor_ddelta_ij_dAmn() to ave_pcs_tensor_ddeltaij_dAmn() for consistency.

Import fix.

Set up the rdc and pcs flags in the __init__() method.

Modified the dfunc_population() gradient function to handle both RDCs and PCSs.

Modified the func_population() target function to handle both RDCs and PCSs.