Support IN operator.

[chakrit]

Not sure this is part of #49 but i think this is a separate issue since it is input-only and does not require full output binding and also a much more common use cases than arrays IMO.

Query: SELECT * FROM members WHERE member_id IN $1

Right now the driver panics with the type []string not being supported. (My record ids are strings)

[chakrit]

Cc : @schumarn

[johto]

IN wouldn't work for this, but if we supported arrays we could do WHERE member_id = ANY($1).

[johto]

To add to my previous response, IN (1,2,3) would internally get converted to = ANY(ARRAY[1,2,3]), so in the end they're the same thing. Also the list after IN can't be parameterized, so we'd have to do something like #233 to support this, and I really would rather not go there.

I don't see any new feature here (other than passing in a slice as an array), so I'm closing this one. Let's keep the discussion about supporting arrays where it belongs.