Allow list type for trait properties

[antirotor]

Problem

Currently there is no way to add "sequential" data to trait. This should be ideally something like list in python, but even array of same type items could solve a lot of things - worst case - array of string.

Use cases:

lens data - adding lens specific data as trait to - lets say image sequence, or camera - is perfect use case of traits. But to handle lens models, you need to store some arrays. For image sequence, focal length (or other parameters) can be animated. So having something like list of focal length values matching frames would solve it.

color management - you could store some color transforms directly in trait, to simplify handling sidecar files in your pipeline.
bounding boxes - store bouding box (or basically any transform) matrix as array. We - for example - need to store axis orientation per asset.
retime - having retime information as a list on trait can help to apply it to data without need to re-render.
frame set just storing list of frames in FileSequence trait could help validating expected frames against actual ones or even creating subsets from whole sequence (like taking every fifth frame from the whole sequence to calculate preview and have that information somewhere).

That's just a tip of others that quicky popped in my mind but I'll add definitely more.