* Removes situations where calling `xs_CRoundToUInt()` and other unsigned inlines would go through extra casts (`uint32_t` > `int32_t` > `uint32_t`).
* Because the native data in the `_xs_doubleints` struct is a union of a double and `uint32_t`, it makes sense to do everything unsigned and convert to `int32_t` if needed instead.