Removed the prune parameter from the backend of the monte_carlo.error_analysis user function.
This was a dangerous parameter used to mimic the 'Trim' parameter from the Modelfree4 program. The
result is bad statistics. The probable reason for the 'Trim' parameter was the failure of
model-free models in the simulations, but this issue was solved using model elimination (see
http://www.nmr-relax.com/refs.html#dAuvergneGooley06).
