Add custom bias.

[sttng]

I guss currently the Bias is calculated according to the IEEE 754 Standard: Bias: 2^(NoOfExpBits-1)-1. So with 8bit exponent a bias of 127, or with 5bit a bias of 15.

It would be nice to set a custom bias akin similar to what mentioned in https://en.wikipedia.org/wiki/Minifloat , a bias of 2.

Otherwise this is all great and useful for education.