Prioritize @extends an @includes within Sass rule sets

When ordering selectors @includes and @extends to me are much more important and I don't want to be 'hunting for them' within a selector's ruleset.

This feels much better to me,
```scss
ul {
  @include span-columns(5);
  border-bottom: 1px solid rgba(0,0,0,.1);
  border-top: 1px solid rgba(0,0,0,.1);
  list-style-type: none;
}
```

as opposed to traditionally,

```scss
ul {
  border-bottom: 1px solid rgba(0,0,0,.1);
  border-top: 1px solid rgba(0,0,0,.1);
  list-style-type: none;
  @include span-columns(5);
}
```