Test case for loooong page numbers in paginated results seems to cause SQL error
Clamp limit values to be unsigned integers.

This solves large page numbers potentially turning into scientific
notation when being formatted into queries. It also further safeguards
against SQL manipulation.

Refs #GH-1263
Stop calling limit() twice on the same data.

DboSource::limit() now follows its documented input types, passing an
already formatted LIMIT string will result in LIMIT 0. Remove useless
array merging as well.
Update limit() for Sqlite.

It should behave as the parent class does.
Update limit() for Postgres

It should work like the parent class.
Update limit() in SQLServer to handle large page numbers as well.