This experimental change makes it possible to:
* Avoid runtime errors due to name typos
* Achieve compile-time guarantees about name matching and usage
* Force widget functions to be name-agnostic by being polymorphic
in their name type
* Clean up focus handling by making it possible to pattern-match
on cursor location names
The change also made many types more heavyweight and in some cases
this is unpleasant when we don't want to have to care about names.
But in those cases we can just use 'n' or '()' depending on how
concrete we need to be. I'm not yet sure how this is going to play
out in practice.
instance for Widget
- This makes the module layout more predictable since Brick.Widgets.Core
now (mostly) only contains widgets and widget transformations
- Utility functions closely related to types are now in Brick.Types
- Brick.Types.Internal contains types used internal by the renderer,
some are re-exported by Brick.Types
