Adds a custom sized type for the world tile rectagle.
This allows us to better express intent.
It also allows us to make certain globals smaller, e.g. `THEME_LOC`.
This matches the behaviour of inventory cell hit logic. Previously it was possible to click exactly on a border and be unable to put an item in the stash.
Gleb Mazovetskiy
ephphatha
Anders Jenbo
Juliano Leal Goncalves