relax SVN archive

Removed a debugging commenting out in the pcs.set_errors user function definition.

Implemented the pcs.set_error user function.

Implemented the rdc.set_errors user function.

Added calls to rdc.set_errors and pcs.set_errors in the missing data N-state model system test script.

These user functions currently do not exist, but are needed as the data files contain no errors.

Modified the missing data system test script to include Monte Carlo simulations.

This is to cover untested code paths.

Fix for the missing PCS data in the N-state model Monte Carlo simulations.

This was caught by the N_state_model.test_mc_sim_failure system test.

Modified the N_state_model.test_mc_sim_failure system test to include missing PCS data.

This is to catch another bug.

Fix for the bug caught by the N_state_model.test_mc_sim_failure system test.

If no RDC error is present, then the returned error from the N-state model analysis specific method
return_error() is None.

Created the N_state_model.test_mc_sim_failure system test to demonstrate a bug in the N-state model.

This appears to be a problem with Monte Carlo simulations when data is missing.

The N-state model grid search optimises each tensor separately when only tensors are optimised.

This massively collapses the grid search size from inc**(5*N) to N*inc**5, where inc are the number
of increments per dimension and N is the number of alignments, making a grid search possible.