* `std.mem.Compare` is now `std.math.Order` and the enum tags
renamed to follow new style convention.
* `std.mem.compare` is renamed to `std.mem.order`.
* new function `std.math.order`
This change was mostly made with `zig fmt` and this also modified some whitespace. Note that in some files, `zig fmt` produced incorrect code, so the change was made manually.
All four of these can be represented in fewer characters with
expressions, which will be guaranteed to happen at compile-time, and
have the same or better precision.
The other math constants here which depend on function calls could be
similarly removed if and when #425 is solved. However I left them for
now since Zig does not eagerly evaluate functions with comptime parameters.
