LearnBoost/stylus — pull request #661 by jasonkuhrt (2012-05-09 00:59:21+00:00)
Title: Let add-property be used as a mixin or a function

- This definition allows add-property to be used as a mixin
- It has the same effect as interpolation but allows users to opt for a functional style
- It simplifies the documentation of add-property in that we don't need to specify that add-property only works as a function