BQS — issue: a new (convenient) method

During BQS implementation we found that a convenient method retrieving
only identifiers of the citations from the query collection would
dramatically improve the performance and make the implementation easier.
It is, indeed, a convenient method, not a new functionality - because
the same can be achieved by creating a collection using a list of
'excluded' attributes. Such list would need to contain all attributes
except of an identifier which may not be so easy to implement (both on
server and client side). Also, it would require to create always a new
collection just for the purpose of retrieving pure identifiers. To have
this convenient method make simply life easier.

Resolution:
To add a new method into module DsLSRBibQuery in the interface
BibRefCollection:

DsLSRBibObjects::BibRefIdentifierList retrieve_all_ids()
raises (LimitExceeded);

see above