Add postfixes to numbers in dd

This is sort of a wip, it might need a little bit of editing/improvement.

What this pr does:

It allows you to specify numbers like 1g and 1000m Specifically it recognises 4 values:

b=512 k=1024 m=1024^2 g=1024^3

Reference on the numbers: https://www.unix.com/man-page/FreeBSD/1/dd/

Why the new libs:

Proptest:

I use this for testing, it works great and helped me identify 2 critical-ish bugs

Num:

I needed this for making getInt accept all numbers