Release/0.4.0

[colmsnowplow]

This is the release PR for the first addition of filtering.

It contains all of the changes from #60, squashed into one commit, as well as fixes for lint issues across the project.

Apologies for needing to create a new PR, I forgot I wasn't on a release branch. Hoping it's easy enough to approve since the difference is minimal.

The only thing to call out is that I changed some previously exported methods to be unexported in order to appease the linter - I think this doesn't cause problems but not 100% certain.

Release TODO (once any change requests are resolved):

• Identify and carry out testing required for production release (release rc if needed)
• Change date in CHANGELOG

[paulboocock]

LGTM, I don't see much need to load test here as nothing changes for existing paths. It seems unlikely that filtering will pose any negative performance issues (famous last words) but if anything unexpected was to occur then we should be able to patch as we go pretty quickly. Particularly as this is the first version of filtering that is likely to evolve over the coming months I don't feel it's worth much further exploration around its performance characteristics.

[colmsnowplow]

@paulboocock I agree on load testing - is there any other kind of testing for filtering that we think is necessary, or would you think that the unit tests I've written should suffice?

[paulboocock]

@paulboocock I agree on load testing - is there any other kind of testing for filtering that we think is necessary, or would you think that the unit tests I've written should suffice?

I think the unit tests, along with the popular fields we expect to be used being tested manually is sufficient.