Add topLevelCommentId field to comments.

[cerupcat]

This allows childComments to know what the top most parent comment is by adding a topLevelCommentId to each childComment.

[SachaG]

Awesome, thanks!

[cerupcat]

Great - thanks SachaG. You're fast! :)

[SachaG]

Taking another look at this, I don't think we can keep that migration. There's three nested forEach loops in there, and I'm not sure if that's a good idea for sites like Crater that already have a lot of comments…

Maybe we just need to leave current data alone and assume the topLevelCommentId property might not always exist?

[cerupcat]

Yeah, I mean, if people don't need this for old comments threads, then it shouldn't be a big deal to not have a migration. I was't sure how to do the migration any simpler.

[SachaG]

Yeah I don't know how you could do it simpler either. It's more about doing it with https://github.com/percolatestudio/meteor-migrations or some similar system that can account for how long it'll take. Telescope's current migrations system is pretty bare-bones, so it can mess up with the deploy process.