Renaming priority_queue_local::loser_tree to int_merger, because that's what it is.
Refactoring pq_ext_merger code.
Adding interceptor class priority_queue_local::loser_tree to abstract common code.
Extracting multi_merge() function from int/ext_array into decendent class int/ext_merger.
Extracting multi_merge_k() method from both int/ext_mergers.
Extracting multi_merge_f() function from PQ's int/ext_mergers.
Reducing complexity of "magic" loser tree step macro.
Splitting int_merger::insert_array() into append_array(), new_player and insert_array into array list.
Splitting ext_merger::insert_segment() into append_merger and loser tree tools.
Making is_array_empty()/is_segment_empty() work the same in ext/int_merger.
Extracting compact_tree() into loser_tree from int/ext_merger.
Extracting double_k() into loser_tree from int/ext_merger.
Fixing problem with tree by making Arity not only a power of two.
Moving free_slots into common loser_tree class.
Moving rebuild_loser_tree() and init_winner() into loser_tree.
Moving actual loser_tree (as Entry[]) into corresponding class.
Refactoring attributes of int/ext_merger
Creating arrays_base containing common attributes.
Recombining int/ext_array and int/ext_merger with loser_tree as subobject.
Fixing compilation with parallel mode.