Switch from Hexbins to Census Tracts

[johnclary]

As discussed here, we're switching from hexbin aggregation to census tracts.

The app needs to be updated to display and query for census tract origins/destinations instead of hexbins. Dependent on the API being updated via this issue

[johnclary]

@mateoclarke i think dockless-dataviz will just work once we update the API to return census tracts via this PR: https://github.com/cityofaustin/atd-dockless-api/pull/49.

[mateoclarke]

Now that the API code update is deployed, it looks like you were right @johnclary. The new polygon shapes come down with the API. I don't love the way it looks and there's a bug with the section color highlighting click that I'm going to log in a separate issue.

Here's what April's downtown data looks like with the default zoom and then zoomed way out. I wonder how useful this is and if we need to revisit scaling the height again.

more or less default zoom

zoomed way out