Add support for Float24

24 bit precision floating point is also not supported natively by the CPU.
The code may be generalized using templates to create a custom precision floating point.
e.g.
```
template <int MANTISSA, int EXPONENT> class Float;

typedef Float<10, 5>   Float16;
typedef Float<16, 7>   Float24;
typedef Float<23, 8>   Float32;
typedef Float<52, 11>  Float64;
```