File\Csv: use Fetchable instead of BaseQuery
Data\BaseQuery: rename to Data\SimpleQuery

BaseQuery should no longer be abstract but be usable as is as soon as
we stripped ResultSet-specific tasks. As "Base" suggests something that
must be extended, the name no longer fits. So this is SimpleQuery right
now.
Fix inline pie reload.

refs #6124
Merge remote-tracking branch 'origin/master' into feature/query-interfaces-6018