This file contains mixins that make it easy to turn any selector into
an icon. You use them in the following way:
```less
@import "octicon-mixins.less";
.entry .disclosure-arrow {
.mini-icon(arr-collapsed);
}
.entry.expanded .disclosure-arrow {
.mini-icon(arr-expanded);
}
```
There is also the `.mega-icon` mixin, and you are free to pass a size
as a second parameter, like this: `.mega-icon(octocat, 64px)`
