add zmij

[lemire]

There are claims that this lib could be 2x faster than the best alternatives:

https://github.com/vitaut/zmij

[jaja360]

We already have it ;) #52

[jaja360]

I just found this one, which we don't have yet : https://github.com/xjb714/xjb
Maybe it's better to wait a stable version before adding it to our benchmark. It's still updated continuously.

[lemire]

Oh!!!

[lemire]

Silly me.