Refactoring for endless running

By now, you've properly noticed a pattern. Every time we add a new feature, we start by refactoring the old code to make it easier to add it. This is generally a good practice in most forms of software development, and we'll be following that same pattern now. We identified a couple of code smells while creating the infinite background, so let's clean those up now, starting with dealing with all those casts.

f32 versus i16

We had to cast values several times to go from i16 to f32 and back again. This isn't a safe operation; the maximum of f32 is orders of magnitude larger than the maximum of i16, so there's the potential for our program to crash on a big f32. HtmlImageElement uses u32 types, so all the casting to make the compiler shut up isn't even correct. We have two choices here:

• Take our data types (such as Rect and Point) and make them match HtmlImageElement.
• Set Rect and any other domain object to...