Recent Phobos changes

[Jason House]

There's been a flurry of commits lately. I noticed two strange things:
1. Unlike other intrinsics, bswap was not marked nothrow (only pure). This seems odd considering what the function does.
2. The math changes removed a lot of float-based prototypes when adding faster functions. That will cause difficulty for those who use floats. Ignoring speed loss for conversions, this will also require explicit casts.

Are these bugs, or am I missing something?