[Toybox] human_readable top header.

[makepost at firemail.cc]

> whereas toybox is now back to unreasonably small units on the same laptop:
> 
>  Mem: 16364136K total, 12297484K used,  4066652K free,  1187844K buffers
> Swap: 33300476K total,   498780K used, 32801696K free,  3706260K cached

Can commas between thousands fit in the line while keeping the K? Like in Total Commander. Alternatively, fraction M with one point and no lost precision. Kilobytes are a point of interest when you're optimizing something on a system with few free left, regardless of the total amount.