This has little or no effect on the optimized build
but significantly improves performance of the headless debug build
`timedemo_test` on my machine goes from 3s to 2s.
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`.
* Use appropriate types for size constants in control.cpp
* Declare constexpr value for iterating over the cells in a stash grid
* Use appropriate type for UIRectangle dimensions
Gleb Mazovetskiy
Andrew James