Use std namespace; improve naming to queue pending objects.
Reorganize "conclude_operation". Additional cleanup.

We don't always want to check if we have all the objects (example: timeout).
Additionally, this is causing the code double check almost everywhere.
Instead of trying to fetch our context out of the ENTER_INTEREST messages
we should keep track of it as part of the interest object.
Fix typo in DistributedObject that would be a bug in the future.