Per-connection type parser overrides

[whitelynx]

I've been looking at the possibility of implementing a custom type parser for PostGIS's geometry type, using the wkx package to parse the (E)WKB it serializes as. Currently, I have a query working that gets the type OID from the database, and I have the type parser working correctly using require('pg').types.setTypeParser(); it's returning a Buffer. However, there's a big hurdle to using this in my project (a web frontend for postgres, web-pgq) - since the OIDs for types introduced by extensions may change between databases (or even on the same database over time), I can't connect to 2 databases and have the type parser work as expected on both.

I can partially work around this by registering and unregistering the type parser before and after each query, but then we get into race conditions if 2 connections are being queried simultaneously... so that's not really a tenable solution.

Could support be added for setting custom type parsers on a per-connection basis?

[brianc]

This is definitely in the works - will leave this open so I can circle back around once it's done!

[whitelynx]

Aah, ok... I had actually started a branch with an implementation yesterday. I can still submit a PR if you'd like.