segment_traits support

[ramnes]

Hey team!

Segment allows user traits to be passed along a track event. PostHog do receive the traits in a segment_traits field of events, but do not use the data to update the user. Do you have any plan to support this?

In the meantime, I'll work around by calling identify rather than passing the traits along, but it adds more events and I would have preferred to keep identify for when users login or change their info.

Happy to answer any question if something isn't clear. :)