WIP: Add support for requesting 'total record count' when issuing paged queries

DO NOT MERGE:

These commits add support for requesting the "total record count" for any paged query.

Functionally, I think this PR is complete, but I failed to update some docstrings based on the changes in return types for some functions, and I didn't update the general documentation at all.  I'll submit another commit for that ASAP.