Implement DbQuery::Category field.

Refs #4782
Implement data processing options (DbConnection::categories).

Refs #4782
Add script constants for the DbCat* filter categories.

Refs #4782
Add documentation for the DbCat* filters.

Refs #4782
Remove unused methods from IdoMysqlConnection.

Refs #4782
Merge branch 'feature/ido-options-4782' into next

Fixes #4782