Note about future Bindings type
SqlColumn is now its own type
Get rid of useless Mark
Dedent foldPrimQuery
Merge branch 'master' into pgtypes
Make abs, negate, lower and upper elements of PrimQuery
Add aggregators BoolAnd and BoolOr to PrimExpr
Use OpCat instead of OpOther "||" and print "||" for OpCat rather than "+"
Merge branch 'master' into pgtypes

Conflicts:
	Opaleye/Aggregate.hs
	Opaleye/Operators.hs