Remove some unnecessary debug.hpp inclusions, and some unused template instantiations.
In directory_map_write_manager_t, use one coroutine per connection instead of one per message.
Check return value of key_2_to_1 everywhere.
Make is_safe_for_us_to_be_primary_helper() and is_safe_for_us_to_be_primary() more consistent in how they set return values.
Fix minor stylistic errors.