Add support for query timeout

[ghivert]

Hi!

Currently we have no way to customise the query timeout. According to pgo#50, it should be easy to add timeout, and we could do this in a nice way.
I'd be happy to submit a PR for the feature, but I think we could gain to design a nice API.

Do you have any opinion on the subject?

[lpil]

Yes lets get this done for sure.

I want to rework the whole API of this package, so I'm open to any ideas. I was likely going to use a builder API.

[ghivert]

Builder API for what part of the API exactly? The connection? The query execution?
I struggle a bit finding out what part of the API you're not happy with.

[lpil]

The whole API. I think currently it's a bit awkward for most uses and it's hard to extend presently.