This implements all traits inside of core::num for all the primitive types,
removing all the functionality from libstd. The std modules reexport all of the
necessary items from the core modules.
This strips out all string-related functionality from the num module. The
inherited functionality is all that will be implemented in libcore (for now).
Primarily, libcore will not implement the Float trait or any string-related
functionality.
It may be possible to migrate string parsing functionality into libcore in the
future, but for now it will remain in libstd.
All functionality in core::num is reexported in std::num.
This removes the TotalOrd and TotalEq implementation macros, they will be added
later to the numeric modules (where the other comparison implementations live).
