Implement orderBy.
Merge pull request #60 from hesselink/implement-orderby

Implement orderBy.
Implement 'limit'.
Implement offset.
Merge pull request #64 from hesselink/implement-limit

Implement 'limit'.
Erik Hesselink added ORDER BY and LIMIT
Update TODO.md about OFFSET
Unpackspec pc boilerplate
ExprArr: add Num instance.

Makes writing where/restrict expressions much nicer.
cast
Dubious QueryRunner instance for nested Maybes
ExprArr: lower, coalesce, cast
Drop haskelldb constraint
Merge remote-tracking branch 'hesselink/implement-offset'