programming ligatures

[Krux02]

I would just like push a bit of attention to the programming font 
[FiraCode](https://github.com/tonsky/FiraCode). It is a font that intends to 
make sourcecode more readable by visualizing common operators such as `!=` and 
`<=` with symbols that look more like the math symbols `≠` and `≤`, but without 
destroying the vertical alignment of characters. It like to mention it, because 
it just got support for Nim ligatures :D