relax SVN archive

Bug fix for the unpacking of results from the torsionless isotropic cone frame order model.

The optimised cone angle was being set to the order parameter in cone_s1.

Fix for the pcs.back_calc() user function for when multiple structures are loaded.

Fix for rdc.read() when neg_g_corr is set to True and the RDC list contains entries with None.

The negative gyromagnetic ratio correction flag neg_g_corr is now available in the rdc.read() user fn.

Better identification of the molecule end in the internal PDB reader.

HETATMs after a TER are now considered part of the same molecule, as they should be.

The sign of the RDC can be inverted to correct for the negative 15N gyromagnetic ratio.

Missing import!

Added another check to iso_cone_S_to_theta() for bad order parameters.

This time the check is for order parameters less than -0.125.

Implemented Monte Carlo simulations for the N-state model.

Created a API common set_selected_sim() method for a single global model.

The method is called _set_selected_sim_global() and simply puts the select_sim bool list into the
cdp.