Base should be baked into countertop

[slifty]

As part of #153 I think it will make a lot of sense for all of the "base" and "core" functionality to get merged into countertop

This means the flow for a developer would be to import countertop and do whatever they want to do without needing to worry about importing a bunch of random "base-error" or "base-interface" junk. Countertop will truly be the entry point not just for appliance users but for appliance developers. This will also make it easier to make sure a countertop + appliance pair is in sync in terms of what version of constants exist instead of updating a bunch of redundant dependencies.

This will mean defining a lot of the content in https://github.com/tvkitchen/base in here, and eventually archiving that repository.

[slifty]

I don't think there's any good reason to import the errors package / classes. Most of those were just there to support... type checks.