Add emptyColumns feature

[hdodov]

A small and simple feature that I really need in my current project. If you specify 3 columns, but you have only 2 items, the third column is empty and takes up space, which ruins the design.

If you’re able to render only 2 columns when there are 2 items, even if you specified 3 columns, you can either center the columns or make them distribute the third column space. This makes things look nicer.