Missing mixins

[botteu]

Great lib! But it seems to be missing some mixins… The ones I've noticed so far are column-span and column-fill.

Is there a reason why these weren't included?

Keep up the good work!

[mkircher]

It appears that first-value-of function is also out. I solved the issue where it was being used in the border-radius mixin (for the experimental block) by creating an nth wrapper:

@function first-value-of( $values ){
  @return nth($values, 1);
}