Query processing: fixed that group by queries can be called from Db.SQL. Reflected in regression tests. Fixes #1593.
Query processor: added unit test of parsing referenced INSERT INTO statement.
Merge branch 'develop' of https://github.com/Starcounter/Starcounter into QueryOptimizerIssue1616
Merge branch 'develop' of https://github.com/Starcounter/Starcounter into QueryOptimizerIssue1616