from_*e_bytes and to_n*_bytes equivalents for floats

[clarfonthey]

These feel appropriate to add for completeness, and would simply chain from_bits or to_bits with the appropriate integer method.

I'll add a PR soon.

This issue has been assigned to @lzutao via this comment.

[nagisa]

Byte order conversions on floats themselves make little sense. The conversions should be done before float’s from/to_bits functions are called.

[nagisa]

Err, I misread the proposal the first time around...

[tesuji]

@rustbot claim