Fix likelihood count for Dynesty

Changes calc_likelihood_count for Dynesty to include the internal counts from the sampler. This fixes the discrepancy between the saved number and the number displayed in the log files as mentioned in #516 (closed).

Any calls to likelihood prior to sampling (e.g. from timing the likelihood here) are still included, however, these calls could be excluded if prefered.

I chose to change calc_likelihood_count over adding something in _generate_result so the number saved to the result file matches the output of this method to avoid confusion if the user called the method elsewhere.