Add support for Float24

[TheNicker]

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;

[acgessler]

Belated reply: would love to, but don't currently have the time. Do you want to have a stab at it?

[TheNicker]

I would love to have this class implemented but it's on a low priority right now. it's needed for reading 24 bit Float TIF images. Moreover I am not completely familiar with the code or the theory behind it so it'll be an effort so currently I believe that you'll do a better job faster