[DEV] Check Lost and InProgress

The current algorithm work incomplete in a case when a reader gets lost and one of it in progress transactions removed because another alive reader has the same transaction. In the case such in progress transaction will be in progress forever. There is no absolute rule to remove it from in progress. The only way is to list such transactions somewhere and check periodically status of Reader.

Start by tracing the current algorithm for lost readers and in-progress transactions; the issue does not name a file or test. Determine how a transaction can remain in progress after its reader is lost, then define and verify periodic reader-status checking so such transactions are eventually handled.

Written by the indexing model from the issue text.