(rasqal_results_compare_variables_equal): Renamed from rasqal_results_compare_equal
Hide rasqal_results_compare internals
Start porting compare_results api to rsaqal_results_compare

(rasqal_new_results_compare): Add label args

(struct rasqal_results_compare_s): Store world, query results, labels
and log data.

(rasqal_results_compare_set_log_handler): Added

(rasqal_results_compare_compare): Added.  Name needs to change

Update test code