DDS15 — Clarify definition of counts in Plain Communication Status

The second table in 2.2.4.1 (the one that starts with "SampleLostStatus") has confusing definitions of the "counts" in various plain communication status.

Certain "statuses" simply report events that occur within the Entities. Sample Lost is a good example of this. When a sample is lost, it's lost for good and not coming back. Therefore we expect total_count_change to be nonnegative. In this case the total_count definition is clear.

Other "status" are ways to report some aspect of the state of the Domain to the application. Inconsistent Topic is an example of this. Since remote Entities can change at any time, the count of inconsistent topics may decrease (for example, when a Topic owned by a remote Participant is deleted). For the "statuses" in this category, the wording of the definition of total_count (and perhaps other attributes) is confusing since it starts with "Total cumulative count..." just like the one for Sample Lost.