Fixing uninitialized member in hash_map compare, indenting.
Changin hash_map::node::next()/deleted() to set_next()/set_deleted().
Changing default item parameter of hash_map to n = 0.
Fixing memory leak in hash_map during reorganizing buckets_ structure.
hash_map: fixing unclosed requests which are lost in block_cache::clear().
Cleaning test_hash_map, adding stats output and more iterations.