Remove any and specify types in the editor

[sehilyi]

Was just poking around with the editor to expose some of this Twitter behavior, cleaned up a few things. A general observation is that there is liberal use of any, which makes TS utility extremely limited here.

Originally posted by @manzt in #692 (comment)

[sehilyi]

Actually, this is an issue in the repo in general (not specific to the editor). I will continuously remove any when updating codes.

We will eventually need type definitions for HiGlass-related functions/variables, such as BarTrack which is a parent class of gosling-track.

[manzt]

That's a great idea, especially as we built out Gosling further!